Biomass blending fuel conveying system and biomass blending system

Abstract

The present application relates to a kind of biomass mixed combustion fuel conveying system and biomass mixed combustion system, biomass mixed combustion fuel conveying system includes multistage closed conveying device, each stage closed conveying device is in turn connected along the direction of primary air duct of fuel storage to the burner of boiler, the feed inlet of first stage closed conveying device is communicated with the discharge port of fuel storage, the discharge port of last stage closed conveying device is communicated with the primary air duct of the burner of boiler, in the above biomass mixed combustion fuel conveying system, multistage closed conveying device in series is used to realize long-distance conveying of material, unlike pneumatic conveying device, the problem that resistance is greater as distance is longer does not occur, the sealing requirement of closed conveying device's conveying pipe is not high, and the problem of easy to appear blockage does not occur, and the problem of cooler leakage does not occur, the problem that long-distance material conveying cost is higher can be effectively solved.

Description

Technical Field

[0001] This invention relates to the field of boiler co-firing technology, and in particular to a biomass co-firing fuel conveying system and a biomass co-firing system. Background Technology

[0002] Currently, the biomass co-firing technology implemented in coal-fired power plant boilers both domestically and internationally mainly adopts pneumatic conveying, which is divided into dilute phase conveying and dense phase conveying. However, due to the low density of biomass fuel, dense phase conveying often suffers from problems such as low conveying efficiency. Therefore, dilute phase conveying is often used for biomass fuel transportation both domestically and internationally, with the material-to-gas ratio generally controlled at around 3 to 8.

[0003] While using pneumatic conveying for biomass fuel blending is feasible and currently the most common method, this technology still has certain technical drawbacks, mainly including:

[0004] (1) Biomass co-firing systems are often modified based on existing boiler units. Due to factors such as construction site limitations, biomass storage silos and other devices for storing biomass fuel are far from the boiler unit, possibly exceeding 300m. The long conveying distance will inevitably increase the resistance of pneumatic conveying and increase the system operating costs.

[0005] (2) Due to the long conveying distance and high pipeline resistance, a fan with a high pressure head is required to provide power. At this time, the sealing of the unloading valve is very important. If the sealing is not good, it will cause air leakage during conveying, and in severe cases, it will affect the material discharge of the system.

[0006] (3) The pneumatic conveying system needs to maintain a high conveying speed during operation, otherwise it will cause blockage of the conveying pipeline. However, because the pneumatic conveying pipeline is long, it is difficult to determine the location of the blockage. When the system is blocked, it is difficult to deal with it. In particular, when the biomass material has a high moisture content and a large particle size, the probability of pipeline blockage will increase significantly.

[0007] (4) When the flow rate of pneumatic conveying is high, it will cause serious wear to the pipeline, especially in areas such as bends. All bends and valves in the conveying system must be made of wear-resistant materials, such as wear-resistant ceramic elbows and ceramic valves, which will greatly increase the investment cost of the system.

[0008] (5) Because the coal-fired power plant boiler is large, multiple conveying pipelines need to be set up to ensure stable combustion of the boiler. For example, each floor of the four-corner tangent boiler needs to be equipped with at least 2 or 4 burners, and the front and rear wall opposed boilers also need to be configured according to the number of burners on each floor, which further increases the investment cost of the system.

[0009] (6) Because biomass fuel has a high volatile content, the temperature of the conveying air needs to be reduced as much as possible during the pneumatic conveying process. This requires the addition of air cooling to cool the high-temperature air generated by the high-pressure blower. This process will increase investment and system operating costs. On the other hand, if the cooler leaks, water from the cooler will enter the conveying air and mix with the biomass fuel, which will greatly increase the risk of blockage in the conveying system and affect the safe and stable operation of the system. Summary of the Invention

[0010] The first objective of this invention is to provide a biomass blending fuel transportation system that enables the transportation of biomass fuel using a non-pneumatic conveying method, thereby avoiding problems such as long transportation distances, high resistance in pneumatic conveying, high requirements for sealing, difficulty in handling pipeline blockages, cooler leaks, and high costs.

[0011] A second objective of this invention is to provide a biomass co-firing system that includes the above-described biomass co-firing fuel delivery system.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A biomass blending fuel conveying system is provided for conveying biomass fuel from a fuel storage silo to a boiler. The biomass blending fuel conveying system includes a multi-stage closed conveying device. Each stage of the closed conveying device is connected in series along the primary air duct from the fuel storage silo to the burner of the boiler. The inlet of the first stage closed conveying device is connected to the outlet of the fuel storage silo, and the outlet of the last stage closed conveying device is connected to the primary air duct of the burner of the boiler.

[0014] Optionally, the enclosed conveying device is a tubular chain conveyor or a tubular belt conveyor.

[0015] Optionally, the closed-loop conveying device includes a material outgoing pipe section and a material return pipe section connected in series. The material outgoing pipe section is provided with an inlet of the closed-loop conveying device at the end away from the material return pipe section. The material return pipe section is provided with an outlet of the closed-loop conveying device at the connection between the material outgoing pipe section and the material return pipe section. The material return pipe section is provided with a return port of the closed-loop conveying device at the end away from the material outgoing pipe section. The return port of the first-stage closed-loop conveying device is connected to the material outgoing pipe section of the first-stage closed-loop conveying device through a return pipe. The return ports of the remaining closed-loop conveying devices are connected to the material outgoing pipe section of the next-stage closed-loop conveying device through return pipes.

[0016] Optionally, the inlet of the first-stage enclosed conveying device is sealed and connected to the outlet of the fuel storage tank through a first unloading system. The first unloading system includes an unloading conveying device, a first unloading pipe, and a first buffer silo. The inlet of the unloading conveying device is connected to the outlet of the fuel storage tank, and the outlet of the unloading conveying device is connected to the first buffer silo through the first unloading pipe. The outlet of the first buffer silo is connected to the inlet of the first-stage enclosed conveying device.

[0017] Optionally, the two adjacent closed conveying devices are connected by a second unloading system, which includes a second unloading pipe and a second buffer silo. The outlet of the upper-level closed conveying device is connected to the second buffer silo through the second unloading pipe, and the outlet of the second buffer silo is connected to the inlet of the lower-level closed conveying device.

[0018] Optionally, the final closed conveying device is arranged around the boiler, and the discharge port of the final closed conveying device is connected to the primary air duct of the boiler burner through a frequency conversion unloading valve. The frequency conversion unloading valve is used to adjust the unloading amount of the discharge port of the final closed conveying device according to a preset frequency.

[0019] Optionally, the boiler is provided with one or more layers of burners, each layer of burners includes multiple burners, and the last-stage closed conveying device is provided with the same number of discharge ports as the number of burners. The discharge ports of each closed conveying device are sequentially connected to the primary air ducts of the one or more layers of burners through the variable frequency unloading valves. The total conveying capacity of each variable frequency unloading valve is less than or equal to the conveying capacity of the last-stage closed conveying device.

[0020] Optionally, the biomass blending fuel conveying system further includes a non-flammable gas supply device, which is used to convey non-flammable gas into the conveying pipes of each of the closed conveying devices.

[0021] Optionally, the non-flammable gas supply device includes a gas source, a gas supply pipeline, and an exhaust pipeline. At least one of the conveying pipes of the closed conveying device is provided with a gas supply port and an exhaust port. The gas outlet of the gas source is connected to the gas supply port through the gas supply pipeline, and the gas return port of the gas source is connected to the exhaust port through the exhaust pipeline.

[0022] Optionally, the conveying pipes of two adjacent enclosed conveying devices are connected by a pressure balancing pipe.

[0023] Optionally, the non-flammable gas supply device further includes a buffer tank, which is connected to at least one of the feed pipes of the enclosed conveying device, and the buffer tank is used to store non-flammable gas.

[0024] A biomass co-firing system includes a fuel storage bin, a fuel delivery system, and a boiler. The fuel storage bin is connected to the primary air duct of the burner of the boiler through the fuel delivery system. The fuel delivery system is any of the biomass co-firing fuel delivery systems described above.

[0025] As can be seen from the above technical solution, the present invention discloses a biomass blending fuel conveying system for conveying biomass fuel from a fuel storage silo to a boiler. This biomass blending fuel conveying system includes a multi-stage closed conveying device. Each stage of the closed conveying device is connected in series along the primary air duct from the fuel storage silo to the boiler burner. The inlet of the first-stage closed conveying device is connected to the outlet of the fuel storage silo, and the outlet of the last-stage closed conveying device is connected to the primary air duct of the boiler burner. In the above biomass blending fuel conveying system, a multi-stage series closed conveying device replaces pneumatic conveying for long-distance biomass fuel transport. By connecting multiple stages of closed conveying devices in series, long-distance material transport can be achieved, avoiding the problem of increasing resistance with longer distances seen with pneumatic conveying. The sealing requirements for the conveying pipe of the closed conveying device are not high, making blockages less likely, and cooler leakage is also eliminated. This effectively solves the problem of high costs associated with long-distance material transport.

[0026] The present invention also provides a biomass co-firing system, which includes a fuel storage silo, a fuel delivery system, and a boiler. The fuel storage silo is connected to the primary air duct of the burner of the boiler through the fuel delivery system. The fuel delivery system is the biomass co-firing fuel delivery system described above. Since the biomass co-firing system adopts the biomass co-firing fuel delivery system in the above embodiments, the biomass co-firing system should have the same beneficial effects as the above biomass co-firing fuel delivery system, which will not be described again here. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the layout structure of a biomass blending fuel conveying system provided in one embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the layout structure of a biomass blending fuel transportation system provided in another embodiment of the present invention;

[0030] Figure 3 This is a partially enlarged schematic diagram of the connection point of the two-stage tubular chain conveyor in the biomass blending fuel transportation system provided in an embodiment of the present invention.

[0031] Figure 4 This is a partially enlarged schematic diagram of the connection between the final stage tubular chain conveyor and the primary air duct of the boiler burner in the biomass co-firing fuel conveying system provided in this embodiment of the invention.

[0032] In the picture:

[0033] 1 is a fuel storage bin; 2 is a first unloading system; 201 is an unloading conveying device; 202 is a first unloading pipe; 203 is a first buffer silo; 3 is a first-stage tubular chain conveyor; 4 is an exhaust port; 5 is an air supply port; 6 is a first return pipe; 7 is a buffer tank; 8 is a second unloading system; 801 is a second unloading pipe; 802 is a second buffer silo; 9 is a second return pipe; 10 is a pressure balancing pipe; 11 is a boiler; 12 is a final-stage tubular chain conveyor; 13 is a burner; 14 is a conveying pipe; 15 is a conveying disc; 16 is a drive chain; 17 is a variable frequency unloading valve; 18 is a primary air duct. Detailed Implementation

[0034] One of the core aspects of this invention is to provide a biomass blending fuel transportation system. The structural design of this biomass blending fuel transportation system enables it to transport biomass fuel in a non-pneumatic manner, which avoids problems such as long transportation distances, high resistance in pneumatic transportation, high requirements for sealing, difficulty in handling pipeline blockages, cooler leakage, and high costs.

[0035] Another core aspect of this invention is to provide a biomass co-firing system that includes the above-mentioned biomass co-firing fuel delivery system.

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Please see Figure 1 , Figure 1 This is a schematic diagram of the layout structure of a biomass blending fuel transportation system provided in one embodiment of the present invention.

[0038] This invention discloses a biomass blending fuel conveying system for conveying biomass fuel from a fuel storage silo 1 to a boiler 11. The biomass blending fuel conveying system includes a multi-stage closed conveying device. Each stage of the closed conveying device is connected in series along the primary air duct from the fuel storage silo to the boiler burner. The inlet of the first-stage closed conveying device is connected to the outlet of the fuel storage silo. The last-stage closed conveying device is arranged around the boiler, and its outlet is connected to the primary air duct of the boiler burner. If the boiler has multiple burners, the last-stage closed conveying device also needs to be equipped with a corresponding number of outlets connected to the primary air ducts of each burner.

[0039] like Figure 1 As shown, boiler 11 is a front and rear wall boiler. Each burner 13 of the front and rear wall boiler 11 is arranged on the two furnace walls opposite to each other. The front and rear wall boilers can be connected to the primary air ducts 18 of each burner 13 in the co-firing layer through the discharge port of the last-stage closed conveying device 12.

[0040] like Figure 2 As shown, in this embodiment, the boiler 11 is a tangentially circular boiler, and the burners 13 of the tangentially circular boiler are distributed on the furnace walls at its four corners. In this embodiment, the primary air ducts 18 of the burners 13 at the four corners of the boiler 11 can be connected in sequence by the final closed conveying device 12 arranged in a ring to the primary air ducts 18 of the burners 13 at the four corners of the boiler 11.

[0041] It should be noted that the boiler 11 is not limited to the two types mentioned above. When the boiler 11 adopts other structures, the final closed conveying device 12 can be adjusted appropriately, or multiple parallel final closed conveying devices 12 can be set to adapt to different boiler 11 structures. This is not limited here. Compared with the prior art, the biomass co-firing fuel conveying system provided by the embodiments of the present invention uses a multi-stage series closed conveying device to replace pneumatic conveying for long-distance biomass fuel conveying. By connecting multiple closed conveying devices in series, long-distance material conveying can be achieved. Unlike pneumatic conveying devices, there is no problem of increasing resistance with longer distances. The sealing requirements of the conveying pipe of the closed conveying device are not high, and blockage is not easy to occur. There is also no problem of cooler leakage, which can effectively solve the problem of high cost of long-distance material conveying.

[0042] In this embodiment of the invention, the enclosed conveying device can be a tubular chain conveyor or a tubular belt conveyor, such as... Figure 4As shown, in this embodiment of the invention, the enclosed conveying device is a tubular chain conveyor. Multiple conveying discs 15 are sequentially and spaced apart inside the conveying pipe 14. Adjacent conveying discs 15 are connected by a drive chain 16. The drive mechanism drives the drive chain 16 to move each conveying disc 15 along the conveying pipe 14 to realize the conveying of materials. The conveying discs 15 are made of anti-static material, and the tubular chain conveyor is equipped with static grounding to prevent static electricity generated by friction from affecting the safety of biomass fuel conveying. Since the tubular chain conveyor adopts a rotary conveying method, it can be connected to all burners 13 of the boiler 11 and fed through the last-stage tubular chain conveyor. By connecting multiple tubular chain conveyors in series, long-distance material conveying can be achieved. Unlike pneumatic conveying devices, it does not have the problem of increasing resistance with longer distances. It does not have high requirements for the sealing of the conveying pipe, and it is not prone to blockage problems. It also does not have the problem of cooler leakage, which can effectively solve the problem of high cost of long-distance material conveying.

[0043] However, it should be noted that, regardless of whether it is a tubular chain conveyor or a tubular belt conveyor, material is not allowed to pass through the location of its drive mechanism. Therefore, in the embodiments of the present invention, as follows... Figures 1 to 3 As shown, the closed-loop conveying device includes a material outgoing pipe section and a material return pipe section. The inlet of the closed-loop conveying device is located at the end of the material outgoing pipe section away from the material return pipe section, and the outlet is located at the material outgoing pipe section and / or the material return pipe section. The return port of the closed-loop conveying device is located at the end of the material return pipe section away from the material outgoing pipe section. The return port of the first-stage closed-loop conveying device is connected to the material outgoing pipe section of the first-stage closed-loop conveying device through a return pipe. The return ports of the remaining closed-loop conveying devices are connected to the material outgoing pipe section of the next-stage closed-loop conveying device through return pipes. This enables the cyclic conveying of materials within the biomass blending fuel conveying system.

[0044] like Figure 1 and Figure 2 As shown, taking a tubular chain conveyor as an example of a closed-loop conveying device, in this embodiment of the invention, the material outgoing pipe section and the material return pipe section of the first-stage tubular chain conveyor 3 are connected by a first return pipe 6. One end of the first return pipe 6 is located upstream of the material outgoing pipe section of the first-stage tubular chain conveyor 3, and the other end of the first return pipe 6 is located downstream of the material outlet of the first-stage tubular chain conveyor 3. In this way, the material in the material return pipe section of the first-stage tubular chain conveyor 3 that has not fallen into the next-stage tubular chain conveyor can be sent back to the material outgoing pipe section of the first-stage tubular chain conveyor 3 through the first return pipe 6, so as to realize the cyclic conveying of materials in the first-stage tubular chain conveyor 3.

[0045] To further optimize the above technical solution, in the embodiments of the present invention, such as... Figure 1 , Figure 2 and Figure 3 As shown, a second return pipe 9 is provided between two adjacent tubular chain conveyors. One end of the second return pipe 9 is connected to the material return section of the next-level tubular chain conveyor, and the other end of the second return pipe 9 is connected to the material outgoing section of the previous-level tubular chain conveyor. In this way, material that does not fall into the boiler 11 or the next-next-level tubular chain conveyor in one of the two adjacent tubular chain conveyors can be sent back to the previous-level tubular chain conveyor through the second return pipe 9 to realize the cyclic transportation of biomass fuel.

[0046] To further optimize the above technical solution, in this embodiment of the invention, the inlet of the first-stage closed conveying device is sealed and connected to the outlet of the fuel storage silo 1 through the first unloading system 2. The first unloading system 2 includes an unloading conveying device 201, a first unloading pipe 202, and a first buffer silo 203. The unloading conveying device 201 includes, but is not limited to, a screw conveyor and a belt conveyor. The inlet of the unloading conveying device 201 is connected to the outlet of the fuel storage silo 1. The outlet of the unloading conveying device 201 is connected to the first buffer silo 203 through the first unloading pipe 202. The outlet of the first buffer silo 203 is connected to the inlet of the first-stage closed conveying device.

[0047] The two adjacent closed conveying devices are connected by a second unloading system 8. The second unloading system 8 has a different structure from the first unloading system 2. The second unloading system 8 includes a second unloading pipe 801 and a second buffer silo 802. The outlet of the upper-level closed conveying device is connected to the second buffer silo 802 through the second unloading pipe 801. The outlet of the second buffer silo 802 is connected to the inlet of the lower-level closed conveying device.

[0048] The final closed conveying device is arranged around the boiler 11, and the discharge port of the final closed conveying device is connected to the primary air duct of the burner of the boiler 11 through the variable frequency discharge valve 17. The variable frequency discharge valve 17 is used to adjust the discharge amount of the discharge port of the final closed conveying device according to the preset frequency, so as to avoid the discharge amount deviation caused by the bend effect as in the pneumatic conveying system.

[0049] like Figure 1 and Figure 2As shown, the boiler 11 is equipped with one or more layers of burners. Each layer of burners includes multiple burners. The final closed-loop conveying device is equipped with the same number of discharge ports as the number of burners. The discharge ports of each closed-loop conveying device are connected to the primary air ducts of the one or more layers of burners in sequence through frequency conversion unloading valves 17. The total conveying capacity of each frequency conversion unloading valve 17 is less than or equal to the conveying capacity of the final closed-loop conveying device. This structural design eliminates the need for branch pipes in the final closed-loop conveying device and ensures that all burners can be fed according to the preset feed rate.

[0050] like Figure 1 and Figure 2 As shown, taking a closed conveying device as an example of a tubular chain conveyor, in this embodiment of the invention, the feed inlet of the first-stage tubular chain conveyor 3 is connected to the discharge outlet of the fuel storage bin 1 through the first unloading system 2, and the discharge outlet of the first buffer bin 203 is connected to the feed inlet of the first-stage tubular chain conveyor 3. The first buffer bin 203 can buffer the impact of falling material on the first-stage tubular chain conveyor 3.

[0051] Accordingly, such as Figure 1 and Figure 2 As shown, two adjacent tubular chain conveyors are connected through the second unloading system 8. The discharge port of the upper-level tubular chain conveyor is connected to the second buffer hopper 802 through the second unloading pipe 801. The discharge port of the second buffer hopper 802 is connected to the inlet of the lower-level tubular chain conveyor. The second buffer hopper 802 can buffer the impact of the material falling from the upper-level tubular chain conveyor on the lower-level tubular chain conveyor.

[0052] To achieve uniform distribution of biomass fuel, in this embodiment of the invention, the discharge port of the final stage tubular chain conveyor 12 is connected to the primary air duct 18 of the burner 13 of the boiler 11 via a frequency conversion unloading valve 17. Further, as... Figure 4 As shown, the boiler 11 is equipped with multiple burners 13, and the final stage tubular chain conveyor 12 has a corresponding number of discharge ports. Each discharge port is connected to the primary air duct 18 of each burner 13 via a variable frequency discharge valve 17. The total conveying capacity of all variable frequency discharge valves 17 is less than or equal to the conveying capacity of the final stage tubular chain conveyor 12. The variable frequency discharge valves 17 can perform gas-solid separation and adjust the discharge rate. By setting the same frequency and ensuring that the maximum conveying capacity of the tubular chain conveyor exceeds the discharge capacity of all variable frequency discharge valves 17, it can be guaranteed that all burners 13 in the boiler 11 have the same co-firing capacity, achieving uniform distribution of biomass fuel. To ensure the safety of the conveying process, in this embodiment of the invention, as follows... Figure 1 and Figure 2As shown, the biomass co-firing fuel transportation system also includes a non-flammable gas supply device, which is used to supply non-flammable gas to each tubular chain conveyor. The non-flammable gas includes inert gases, CO2, N2 and other non-combustible gases, so that the entire biomass fuel transportation process is in a non-flammable atmosphere, ensuring the safety of transportation.

[0053] Specifically, in embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the non-flammable gas supply device includes a gas source, a gas supply pipeline and an exhaust pipeline. At least one closed conveying device has a gas supply port 5 and an exhaust port 4 on its conveying pipe. The gas outlet of the gas source is connected to the gas supply port 5 through the gas supply pipeline, and the gas return port of the gas source is connected to the exhaust port 4 through the exhaust pipeline.

[0054] To ensure a non-flammable atmosphere is formed within each enclosed conveying device, an air supply port 5 and an exhaust port 4 can be provided on each enclosed conveying device and connected to an air source through air supply and exhaust pipes, respectively. However, this method is costly and does not guarantee pressure balance within each enclosed conveying device. Therefore, in this embodiment of the invention, the conveying pipes of two adjacent enclosed conveying devices are connected through a pressure balancing pipe, which ensures that a non-flammable atmosphere is formed within each tubular chain conveyor and that pressure balance is maintained.

[0055] Furthermore, in embodiments of the present invention, such as Figure 1 and Figure 2 As shown, the non-flammable gas supply device also includes a buffer tank, which is connected to the conveying pipe of at least one closed conveying device. The buffer tank is used to store non-flammable gas and is used as a supplement to the gas source.

[0056] Taking a closed-loop conveying device as an example, the first-stage tubular chain conveyor 3 has an air supply port 5 and an exhaust port 4 on its conveying pipe 14. The air outlet of the air source is connected to the air supply port 5 through the air supply pipeline, and the air return port of the air source is connected to the exhaust port 4 through the exhaust pipeline. During the operation of the biomass co-firing fuel conveying system, the air source circulates non-combustible gas into the conveying pipe 14 of the first-stage tubular chain conveyor 3 through the air supply pipeline and the exhaust pipeline.

[0057] exist Figure 1 and Figure 2 In the embodiment shown, the biomass co-firing fuel conveying system consists of a two-stage tubular chain conveyor, namely a first-stage tubular chain conveyor 3 and a final-stage tubular chain conveyor 12. The conveying pipes 14 of the first-stage tubular chain conveyor 3 and the final-stage tubular chain conveyor 12 are connected by a pressure balancing pipe 10. Thus, it is only necessary to set an air supply port 5 and an exhaust port 4 on the first-stage tubular chain conveyor 3, and connect it to the air source through the air supply pipe and the exhaust pipe to ensure the pressure balance in the two-stage tubular chain conveyors.

[0058] In summary, the biomass co-firing fuel conveying system in this embodiment of the invention can replace the existing pneumatic conveying system in the biomass co-firing process, greatly reducing system investment and operating costs. It also solves problems such as high pressure loss, easy material blockage, and pipe blockage and wear when conveying non-uniform materials during long-distance pneumatic conveying. Introducing non-combustible gas into the conveyor greatly improves the safety of the biomass fuel conveying process, ensuring safe system operation. Furthermore, this embodiment of the invention uses a variable frequency discharge valve 17 for unloading, achieving uniform distribution of biomass fuel.

[0059] This invention also provides a biomass co-firing system, which includes a fuel storage silo 1, a fuel delivery system, and a boiler 11. The fuel storage silo 1 is connected to the primary air duct 18 of the burner 13 of the boiler 11 through the fuel delivery system. The fuel delivery system is the biomass co-firing fuel delivery system as described in the above embodiments. Since this biomass co-firing system adopts the biomass co-firing fuel delivery system in the above embodiments, the technical effects of this biomass co-firing system can be found in the above embodiments.

[0060] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A biomass blending fuel conveying system for conveying biomass fuel from a fuel storage silo to a boiler, characterized in that, The biomass blending fuel conveying system includes a multi-stage closed conveying device. Each stage of the closed conveying device is connected in series along the primary air duct from the fuel storage bin to the boiler burner. The inlet of the first-stage closed conveying device is connected to the outlet of the fuel storage bin, and the outlet of the last-stage closed conveying device is connected to the primary air duct of the boiler burner. The closed conveying device is a tubular chain conveyor or a tubular belt conveyor. Each closed conveying device includes a material outgoing pipe section and a material return pipe section connected in series. The material outgoing pipe section is located away from the fuel storage bin. The material return pipe section is provided with an inlet of the closed conveying device at one end, and the material return pipe section and / or the material outgoing pipe section is provided with an outlet of the closed conveying device. The material return pipe section is provided with a return port of the closed conveying device at the end away from the material outgoing pipe section. The return port of the first-stage closed conveying device is connected to the material outgoing pipe section of the first-stage closed conveying device through a return pipe. The return ports of the remaining closed conveying devices are connected to the material outgoing pipe section of the closed conveying device above them through return pipes.

2. The biomass blending fuel conveying system according to claim 1, characterized in that, The inlet of the first-stage enclosed conveying device is sealed and connected to the outlet of the fuel storage tank through a first unloading system. The first unloading system includes an unloading conveying device, a first unloading pipe, and a first buffer silo. The inlet of the unloading conveying device is connected to the outlet of the fuel storage tank, and the outlet of the unloading conveying device is connected to the first buffer silo through the first unloading pipe. The outlet of the first buffer silo is connected to the inlet of the first-stage enclosed conveying device.

3. The biomass blending fuel conveying system according to claim 1, characterized in that, The two adjacent closed conveying devices are connected by a second unloading system, which includes a second unloading pipe and a second buffer silo. The outlet of the upper-level closed conveying device is connected to the second buffer silo through the second unloading pipe, and the outlet of the second buffer silo is connected to the inlet of the lower-level closed conveying device.

4. The biomass blending fuel conveying system according to claim 1, characterized in that, The final stage of the enclosed conveying device is arranged around the boiler, and the outlet of the final stage of the enclosed conveying device is connected to the primary air duct of the boiler burner through a frequency-controlled unloading valve. The frequency-controlled unloading valve is used to adjust the unloading amount of the outlet of the final stage of the enclosed conveying device according to a preset frequency.

5. The biomass blending fuel conveying system according to claim 4, characterized in that, The boiler is equipped with one or more layers of burners, each layer of burners includes multiple burners, and the last-stage closed conveying device is equipped with the same number of discharge ports as the number of burners. The discharge ports of each closed conveying device are connected to the primary air ducts of the one or more layers of burners in sequence through the variable frequency unloading valves. The total conveying capacity of each variable frequency unloading valve is less than or equal to the conveying capacity of the last-stage closed conveying device.

6. The biomass co-combustion fuel delivery system according to claim 1, wherein, The biomass blending fuel delivery system also includes a non-flammable gas supply device, which is used to deliver non-flammable gas into the delivery pipes of each of the closed delivery devices.

7. The biomass co-combustion fuel delivery system according to claim 6, wherein, The non-combustible gas supply device includes a gas source, a gas supply pipeline, and an exhaust pipeline. At least one of the conveying pipes of the closed conveying device is provided with a gas supply port and an exhaust port. The gas outlet of the gas source is connected to the gas supply port through the gas supply pipeline, and the gas return port of the gas source is connected to the exhaust port through the exhaust pipeline.

8. The biomass co-combustion fuel delivery system according to claim 7, wherein, The conveying pipes of two adjacent enclosed conveying devices are connected by a pressure balancing pipe.

9. The biomass co-combustion fuel delivery system according to claim 7, wherein, The non-flammable gas supply device also includes a buffer tank, which is connected to the feed pipe of at least one of the closed conveying devices, and the buffer tank is used to store non-flammable gas.

10. A biomass co-firing system comprising a fuel storage bin, a fuel delivery system, and a boiler, the fuel storage bin being in communication with a primary air duct of a burner of the boiler by the fuel delivery system, characterized in that, The fuel delivery system is the biomass blending fuel delivery system as described in any one of claims 1-9.

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