Biomass fuel preparation system and thermal power generating unit
Patent Information
- Application Number
- CN202610610600.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-06
- Publication Date
- 2026-07-10
Smart Images
Figure CN122357192A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biomass co-firing technology in coal-fired boilers and coal-fired power units, and in particular to a biomass fuel preparation system and a thermal power unit. Background Technology
[0002] The "Action Plan for Low-Carbon Transformation of Coal-fired Power Plants (2024-2027)" proposes biomass co-firing, making full use of biomass resources such as agricultural and forestry waste, desert plants, and energy plants to reduce carbon emissions from coal-fired power units by coupling biomass power generation. The "Draft for Comments on the National Carbon Emission Trading Power Generation Industry Quota Allocation Scheme" explicitly states that units with a biomass co-firing ratio exceeding 10% will not participate in carbon emission quota allocation for the time being, meaning there are currently no regulations on the total carbon composition of the units. The low-carbon action plans of the National Development and Reform Commission and the National Energy Administration, as well as the carbon emission quota allocation scheme of the Ministry of Ecology and Environment of the People's Republic of China, all demonstrate the country's active encouragement of biomass co-firing in coal-fired power units. Baking and carbonizing biomass with heat can improve its grindability and calorific value, making it closer to that of coal. Mixing baked and carbonized biomass with coal for pulverization has less impact on the pulverizing system, resulting in a simpler co-firing system and less unit modification. To obtain a safer and more economical biomass baking and carbonization fuel preparation system, and to fully utilize the waste heat from coal-fired boilers, developing a safe and economical biomass fuel preparation system is of great significance. Summary of the Invention
[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a biomass fuel preparation system that utilizes the waste heat of the flue gas from a biomass roasting and carbonization device to preheat the air about to enter an air preheater, resulting in good heating effect on the air in the air preheater.
[0004] The present invention also proposes a thermal power unit, which includes the above-mentioned biomass fuel preparation system.
[0005] According to an embodiment of the present invention, a biomass fuel preparation system is used in a thermal power unit, the thermal power unit including a coal-fired boiler and an air preheater, the air preheater being connected to the flue gas outlet of the coal-fired boiler via a first pipe, the biomass fuel preparation system including: a first branch pipe, one end of the first branch pipe being connected to the first pipe; a biomass baking and carbonization device, the biomass baking and carbonization device having a receiving space for containing biomass materials, the flue gas inlet of the biomass baking and carbonization device being connected to the other end of the first branch pipe; and a heat exchanger having a first flow path and a second flow path, the flue gas outlet of the biomass baking and carbonization device being connected to the first flow path, and the second flow path being connected to the air inlet pipe of the air preheater.
[0006] According to an embodiment of the present invention, the biomass fuel preparation system, by setting up a heat exchanger with a first flow path and a second flow path, connects the flue gas outlet of the biomass baking and carbonization equipment to the first flow path and the second flow path to the air inlet pipe of the air preheater. The waste heat of the flue gas flowing out of the biomass baking and carbonization equipment can be used to preheat the air about to enter the air preheater. Then, the flue gas flowing directly out of the coal-fired boiler further heats the air in the air preheater. The heating effect of the air in the air preheater is better. After the heated air in the air preheater flows out, it can flow to the furnace of the coal-fired boiler. While assisting combustion, it helps to increase the temperature level in the furnace of the coal-fired boiler. Moreover, the hot air can accelerate the drying and ignition process of pulverized coal, making the combustion more stable and complete, and reducing the loss of incomplete combustion.
[0007] In some embodiments of the present invention, the flue gas outlet of the biomass baking and carbonization equipment is connected to a first branch pipe, the heat exchanger is disposed on the first branch pipe, the first branch pipe is provided with a first dust collector, and the first dust collector is disposed upstream of the heat exchanger.
[0008] In some embodiments of the present invention, the first branch pipe is provided with a first regulating valve, which is located upstream of the first dust collector and is used to regulate the opening and closing of the first branch pipe and the flue gas flow rate in the first branch pipe.
[0009] In some embodiments of the present invention, the flue gas outlet of the biomass baking and carbonization equipment is connected to a second branch pipe, which is connected to the dry slag removal system at the bottom of the coal-fired boiler.
[0010] In some embodiments of the present invention, the second branch pipe is provided with a second regulating valve for regulating the opening and closing of the second branch pipe and the flue gas flow rate in the second branch pipe.
[0011] In some embodiments of the present invention, the flue gas outlet of the biomass baking and carbonization equipment is connected to a third branch pipe, which is connected to the hot secondary air box of the coal-fired boiler.
[0012] In some embodiments of the present invention, a second dust collector is provided on the third branch pipe, and a third regulating valve is provided on the third branch pipe. The third regulating valve is located upstream of the second dust collector and is used to regulate the opening and closing of the third branch pipe and the flue gas flow rate in the third branch pipe.
[0013] In some embodiments of the present invention, an extraction fan is provided on the first branch pipe, the extraction fan being used to guide flue gas from the coal-fired boiler to the biomass baking and carbonization equipment, and a fourth regulating valve is also provided upstream of the extraction fan, the fourth regulating valve being used to regulate the opening and closing of the first branch pipe and the flue gas flow rate in the first branch pipe.
[0014] In some embodiments of the present invention, the biomass roasting and carbonization equipment includes: an equipment body, wherein the accommodating space is disposed inside the equipment body; a feeding bin, wherein the feeding bin is disposed on the upper side of the equipment body and communicates with the accommodating space; and a discharge pipe, wherein the discharge pipe is disposed on the lower side of the equipment body and communicates with the accommodating space.
[0015] According to an embodiment of the present invention, a thermal power unit includes the above-described biomass fuel preparation system.
[0016] According to an embodiment of the present invention, a thermal power unit is provided with a heat exchanger having a first flow path and a second flow path. The flue gas outlet of the biomass baking and carbonization equipment is connected to the first flow path, and the second flow path is connected to the air inlet pipe of the air preheater. The waste heat of the flue gas flowing out of the biomass baking and carbonization equipment can be used to preheat the air about to enter the air preheater. Then, the flue gas flowing directly out of the coal-fired boiler will further heat the air in the air preheater. The heating effect of the air in the air preheater is better. After the heated air in the air preheater flows out, it can flow to the furnace of the coal-fired boiler. While assisting combustion, it helps to increase the temperature level in the furnace of the coal-fired boiler. The hot air can also accelerate the drying and ignition process of pulverized coal, making the combustion more stable and complete, and reducing the loss of incomplete combustion.
[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a thermal power unit according to an embodiment of the present invention.
[0019] Figure label: 100. Thermal power units; 1. Coal-fired boiler; 11. Dry ash removal system; 12. Hot secondary air box; 2. Air preheater; 21. First duct; 22. Flue gas flow path; 23. Third dust collector; 3. Biomass fuel production system; 31. First branch pipe; 311. Exhaust fan; 312. Fourth regulating valve; 32. Biomass roasting and carbonization equipment; 321. Equipment body; 3211. Containing space; 322. Feed hopper; 3221. Gate valve; 323. Discharge pipe; 33. Heat exchanger; 331. First flow path; 332. Second flow path; 34. First branch pipe; 341. First dust collector; 342. First regulating valve; 35. Second branch pipe; 351. Second regulating valve; 36. Third branch pipe; 361. Second dust collector; 362. Third regulating valve. Detailed Implementation
[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0023] The biomass fuel preparation system 3 according to an embodiment of the present invention is described below with reference to the accompanying drawings.
[0024] like Figure 1 As shown, the biomass fuel preparation system 3 according to an embodiment of the present invention includes a first branch pipe 31, a biomass baking and carbonization device 32, and a heat exchanger 33.
[0025] Specifically, the biomass fuel preparation system 3 is used in a thermal power unit 100, which includes a coal-fired boiler 1 and an air preheater 2. The air preheater 2 is connected to the flue gas outlet of the coal-fired boiler 1 via a first pipe 21. It is understood that after pulverized coal and other fuels are burned in the coal-fired boiler 1, flue gas with temperatures reaching several hundred degrees Celsius is produced. This flue gas, after flowing through the various heating surfaces (water-cooled walls, superheaters, economizers, etc.) of the coal-fired boiler 1, still carries a large amount of residual heat. The flue gas with a large amount of residual heat flows through the first pipe 21 to the air preheater 2. The air preheater 2 can use the residual heat of the flue gas to heat the air. The heated air can flow into the furnace of the coal-fired boiler 1, aiding combustion and helping to increase the temperature level inside the furnace. Furthermore, when burning difficult-to-ignite anthracite or high-moisture lignite, the hot air can accelerate the drying and ignition process of the pulverized coal, making combustion more stable and complete, and reducing losses from incomplete combustion.
[0026] like Figure 1 As shown, one end of the first branch pipe 31 is connected to the first pipe 21. The biomass baking and carbonization equipment 32 is provided with a receiving space 3211, which is used to receive biomass materials. The flue gas inlet of the biomass baking and carbonization equipment 32 is connected to the other end of the first branch pipe 31. It is converted into "green fuel" compatible with pulverized coal through the baking and carbonization process and is seamlessly coupled with the existing unit. The processed biomass is discharged through the discharge port and enters the coal mill for pulverization and is sent to the furnace of the coal-fired boiler 1 for combustion.
[0027] The specific process is as follows: the biomass roasting and carbonization equipment 32 processes biomass into easily pulverized, hydrophobic, and high-energy carbonized products under anaerobic conditions. These products are discharged directly from the outlet and sent to the power plant's coal mill for co-grinding with coal, and finally blown into the furnace for co-combustion. This not only utilizes the high-efficiency system of existing thermal power units 100 to achieve large-scale, low-cost energy utilization of biomass, replacing some fossil fuels; but also significantly reduces carbon emissions throughout the entire life cycle due to the combustion of gas generated during roasting and the extended value of biochar itself in areas such as soil improvement. This allows traditional coal-fired power plants to achieve comprehensive benefits of carbon reduction, cost reduction, and increased revenue without changing their main structure.
[0028] The first branch pipe 31 guides the flue gas in the first pipe 21 to the containment space 3211, and the waste heat of the flue gas can be used to realize the baking and carbonization of biomass by the biomass baking and carbonization equipment 32, making the thermal power unit 100 more green and energy-saving.
[0029] In some embodiments, the biomass fuel preparation system 3 further includes a second branch pipe, one end of which is connected to the outside atmosphere and the other end of which is connected to the biomass baking and carbonization equipment 32. A flow regulating valve can be installed on the second branch pipe. The opening of the flow regulating valve in the second branch pipe is adjusted according to the flue gas temperature required by the biomass baking and carbonization equipment 32 to control the air and flue gas ratio to obtain a reasonable temperature for entering the biomass baking and carbonization equipment 32.
[0030] The heat exchanger 33 has a first flow path 331 and a second flow path 332. The flue gas outlet of the biomass baking and carbonization equipment 32 is connected to the first flow path 331, and the second flow path 332 is connected to the air inlet pipe of the air preheater 2. At this time, the waste heat of the flue gas flowing out of the biomass baking and carbonization equipment 32 can be used to preheat the air about to enter the air preheater 2. Then, the flue gas flowing directly out of the coal-fired boiler 1 will be used to reheat the air in the air preheater 2. The heating effect of the air in the air preheater 2 is better, and the combustion assistance is better achieved.
[0031] According to an embodiment of the present invention, the biomass fuel preparation system 3 is provided with a heat exchanger 33 having a first flow path 331 and a second flow path 332. The flue gas outlet of the biomass baking and carbonization equipment 32 is connected to the first flow path 331, and the second flow path 332 is connected to the air inlet pipe of the air preheater 2. The waste heat of the flue gas flowing out of the biomass baking and carbonization equipment 32 can be used to preheat the air about to enter the air preheater 2. Then, the flue gas flowing directly out of the coal-fired boiler 1 will be used to reheat the air in the air preheater 2. The heating effect of the air in the air preheater 2 is better. After the heated air in the air preheater 2 flows out, it can flow to the furnace of the coal-fired boiler 1. While assisting combustion, it helps to increase the temperature level in the furnace of the coal-fired boiler 1. The hot air can also accelerate the drying and ignition process of pulverized coal, making the combustion more stable and complete, and reducing the loss of incomplete combustion.
[0032] In some embodiments of the present invention, such as Figure 1 As shown, the flue gas outlet of the biomass baking and carbonization equipment 32 is connected to a first branch pipe 34. A heat exchanger 33 is installed on the first branch pipe 34, and a first dust collector 341 is installed on the first branch pipe 34, located upstream of the heat exchanger 33. It can be understood that the first dust collector 341 can remove solid particles from the flue gas flowing out of the biomass baking and carbonization equipment 32, leaving relatively clean gas, which then flows to the heat exchanger 33 for heat exchange, preventing solid particles from clogging the first flow path 331.
[0033] In addition, after the flue gas in the air preheater 2 flows out of the air preheater 2 through the flue gas flow path 22, a third dust collector 23 is provided on the downstream side of the flue gas flow path 22. The third dust collector 23 can remove solid particles in the flue gas flowing out of the air preheater 2, leaving relatively clean gas, which then merges with the gas flowing out of the first branch pipe 34 of the heat exchanger 33 after heat exchange with the gas in the second flow path 332. The merged gas can be used together for subsequent flue gas treatment.
[0034] In some embodiments of the present invention, such as Figure 1 As shown, the first branch pipe 34 is equipped with a first regulating valve 342, which is located upstream of the first dust collector 341. The first regulating valve 342 is used to regulate the opening and closing of the first branch pipe 34 and the flue gas flow rate within it. The flue gas flow rate within the first branch pipe 34 can be selected according to the heat exchange requirements of the heat exchanger 33 to meet different usage needs.
[0035] In some embodiments of the present invention, such as Figure 1 As shown, the flue gas outlet of the biomass baking and carbonization equipment 32 is connected to a second branch pipe 35, which is connected to the dry slag removal system 11 at the bottom of the coal-fired boiler 1. The flue gas flowing out of the biomass baking and carbonization equipment 32 replaces the cooling air of the dry slag removal system 11, which helps to reduce the risk of unorganized air leakage in the coal-fired boiler 1, increase the amount of air participating in combustion, and improve the efficiency of the coal-fired boiler 1.
[0036] In some embodiments of the present invention, such as Figure 1 As shown, the second branch pipe 35 is equipped with a second regulating valve 351, which is used to regulate the opening and closing of the second branch pipe 35 and the flue gas flow rate within the second branch pipe 35. The flue gas flow rate within the second branch pipe 35 can be selected according to the cooling requirements of the dry ash removal system 11 at the bottom of the coal-fired boiler 1 to meet different usage needs. At the same time, the flue gas flow rate within the second branch pipe 35 can also be changed according to the heat exchanger 33 in the first branch pipe 34 to balance the heat exchanger 33's heat exchange requirements and the cooling requirements of the dry ash removal system 11 at the bottom of the coal-fired boiler 1.
[0037] In some embodiments of the present invention, such as Figure 1 As shown, the flue gas outlet of the biomass baking and carbonization equipment 32 is connected to a third branch pipe 36, which is connected to the hot secondary air box 12 of the coal-fired boiler 1. The hot air in the third branch pipe 36 can accelerate the drying and ignition process of pulverized coal, making the combustion more stable and complete, and reducing the loss of incomplete combustion.
[0038] In some embodiments of the present invention, such as Figure 1As shown, a second dust collector 361 is provided on the third branch pipe 36. It can be understood that the second dust collector 361 can remove solid particles from the flue gas flowing out of the biomass baking and carbonization equipment 32, leaving relatively clean gas, which then flows to the hot secondary air box 12, to prevent solid particles from re-entering the coal-fired boiler 1, to avoid the contamination of the heating surface caused by a lot of smoke and dust in the coal-fired boiler 1, and to avoid a decrease in heat transfer efficiency.
[0039] like Figure 1 As shown, the third branch pipe 36 is equipped with a third regulating valve 362, which is located upstream of the second dust collector 361. The third regulating valve 362 is used to regulate the opening and closing of the third branch pipe 36 and the flue gas flow rate within it. The flue gas flow rate within the third branch pipe 36 can be selected according to the hot air demand of the hot secondary air box 12 to meet different usage requirements. Simultaneously, the flue gas flow rate within the third branch pipe 36 can also be changed according to the heat exchange demand of the heat exchanger 33 in the first branch pipe 34 and the cooling demand in the second branch pipe 35, in order to balance the heat exchange demand of the heat exchanger 33, the cooling demand of the dry ash removal system 11 at the bottom of the coal-fired boiler 1, and the hot air demand of the hot secondary air box 12.
[0040] In some embodiments of the present invention, such as Figure 1 As shown, the first branch pipe 31 is equipped with an extraction fan 311. The extraction fan 311 is used to guide the flue gas from the coal-fired boiler 1 to the biomass baking and carbonization equipment 32. The extraction fan 311 draws the flue gas at 300℃-350℃ in the first pipe. The extracted flue gas enters the biomass baking and carbonization equipment 32 to heat the biomass pellets from the biomass silo.
[0041] A fourth regulating valve 312 is also provided upstream of the extraction fan 311. The fourth regulating valve 312 is used to regulate the opening and closing of the first branch pipe 31 and the flue gas flow rate in the first branch pipe 31. The fourth regulating valve 312 can control the amount of flue gas extracted from the first branch pipe 34 through the first branch pipe 31 to meet different usage requirements.
[0042] In some embodiments of the present invention, such as Figure 1 As shown, the biomass roasting and carbonization equipment 32 includes an equipment body 321, a feed hopper 322, and a discharge pipe 323. A receiving space 3211 is located inside the equipment body 321. The feed hopper 322 is located on the upper side of the equipment body 321 and communicates with the receiving space 3211. The discharge pipe 323 is located on the lower side of the equipment body 321 and communicates with the receiving space 3211. The feed hopper 322 is connected to the equipment body 321 via a pipe, on which a gate valve 3221 is installed. The processed biomass is discharged through the discharge port and fed into a coal mill for pulverization and combustion in the furnace of a coal-fired boiler 1.
[0043] To achieve the above objectives, the present invention provides a biomass fuel preparation system 3, which is implemented through the following steps: Step 1: Start the coal-fired boiler 1 and its auxiliary systems normally and run them until they reach a stable state.
[0044] Step 2: Start the biomass baking and carbonization equipment 32, open the gate valve 3221 on the feed hopper 322, and the biomass pellets enter the baking and carbonization equipment, maintaining a certain material layer thickness.
[0045] Step 3: Open the fourth regulating valve 312 on the first branch pipe 31 and start the extraction fan 311. Part of the high-temperature flue gas from the coal-fired boiler 1 enters the biomass baking and carbonization equipment 32 to heat the biomass. If the flue gas temperature needs to be adjusted, the flow regulating valve on the second branch pipe needs to be opened.
[0046] Step 4: After a period of time, once the biomass fuel preparation is complete, the prepared biomass fuel is discharged from the outlet, pulverized by the coal mill, and then sent to the furnace of the coal-fired boiler 1 for combustion.
[0047] Step 5: When starting the biomass baking and carbonization equipment 32, it is necessary to select the utilization method of the exhaust gas after heat exchange in the biomass baking and carbonization equipment 32. If the first method is adopted, the flue gas enters the first branch pipe 34, the second regulating valve 351 on the second branch pipe 35 and the third regulating valve 362 on the third branch pipe 36 are closed, the first regulating valve 342 on the first branch pipe 34 is opened and the first dust collector 341 on the first branch pipe 34 is started. After dust removal, the flue gas enters the heat exchanger 33 and exchanges heat with the secondary air from the blower of the coal-fired boiler 1, increasing the temperature of the secondary air entering the air preheater 2. After heat exchange, the flue gas enters the tail flue after the third dust collector 23 of the coal-fired boiler 1 and is discharged into the atmosphere.
[0048] Step 6: If the exhaust gas is utilized in the second way, that is, directly enters the dry ash removal system 11 at the bottom of the coal-fired boiler 1 to replace the cooling air of the dry ash removal system 11, open the second regulating valve 351 on the second branch pipe, and the flue gas enters the dry ash removal system 11 at the bottom of the coal-fired boiler 1 and enters the furnace.
[0049] Step 7: If the exhaust gas is utilized using the third method, that is, after dust removal, the exhaust gas enters the hot secondary air box 12 of the coal-fired boiler 1 and mixes with the hot secondary air before entering the furnace. Close the first regulating valve 342 on the first branch pipe 31 and the second regulating valve 351 on the second branch pipe, open the third regulating valve 362 on the third branch pipe, and start the second dust collector 361. After dust removal, the exhaust gas enters the hot secondary air box 12 of the coal-fired boiler 1, mixes with the hot secondary air, and then enters the furnace of the coal-fired boiler 1.
[0050] Step 8: When it is necessary to shut down the biomass fuel preparation system 3, first close the gate valve 3221 below the feed hopper 322, stop the extraction fan 311, and close the fourth regulating valve 312 on the first branch pipe 31. Then shut down the biomass roasting and carbonization equipment 32, the first dust collector 341, and the second dust collector 361, and close the first regulating valve 342, the second regulating valve 351, and the third regulating valve 362.
[0051] Taking the direct co-firing of biomass in a 320MW subcritical coal-fired boiler in China as an example, this paper introduces and explains the biomass fuel preparation system.
[0052] Coal-fired boiler 1 is a 320MW subcritical, single-stage reheat, natural circulation drum coal-fired boiler. It is a single-furnace, balanced draft, tangential combustion, all-steel frame coal-fired boiler. The furnace width is 14022mm and the furnace depth is 12350mm. It employs a medium-speed coal mill, cold primary air fan, positive pressure direct blowing, negative pressure furnace, and balanced draft pulverizing and combustion system; it is equipped with 5 HP direct-blown medium-speed coal mills, of which 4 are in operation and 1 is on standby. The B-layer burners of coal-fired boiler 1 have undergone micro-oil ignition modification in recent years; this low-NOx burner modification retains the micro-oil ignition function of the B-layer burners. Each coal mill outlet is connected to 4 primary air ducts (Φ508×10mm) after passing through a separator and pulverized coal distributor.
[0053] Combustion System: The main air box is equipped with 5 layers of WR pulverized coal nozzles, with fuel air arranged around the nozzles. Auxiliary air nozzles are arranged between every two adjacent layers of pulverized coal nozzles, comprising half vertically offset and half direct-blowing air. A layer of compact burnout air nozzles is located at the top of the main air box, and a layer of secondary air nozzles is located at the bottom of the main air box.
[0054] A SOFA burner is arranged on the upper part of the main air box, including four layers of horizontally swingable high-level burnout air (SOFA) nozzles.
[0055] Each air chamber of the main burner is equipped with a corresponding secondary air damper. Each corner of the main burner has 12 air dampers and 12 corresponding pneumatic actuators, controlled by linkages. Each corner has four layers of SOFA (Sort-Off Air) nozzles, each corner SOFA has 4 air dampers and 16 corresponding SOFA actuators, and the main burner has 48 pneumatic actuators.
[0056] Table 1 shows the types of coal used in coal-fired boilers and the parameters for co-firing biomass.
[0057] Table 1. Coal type and biomass blending parameters for coal-fired boilers
[0058] A coal-fired boiler 1, with an annual capacity of 70,000 tons of biomass roasting and carbonization fuel, requires the extraction of high-temperature flue gas from the air preheater inlet of the coal-fired boiler 1 into the biomass roasting and carbonization equipment 32 to heat the biomass pellets. The configuration parameters of the biomass fuel preparation system 3 of this invention are as follows: the output of the biomass roasting and carbonization fuel equipment is 8 t / h, and the quantity is 2 units. The maximum proportion of high-temperature flue gas from the coal-fired boiler 1 is 5%, and the parameters of the flue gas extraction fan are: flow rate 25 t / h, pressure head 400 Pa. The extracted flue gas temperature is 300-320℃, and the exhaust gas temperature is approximately 230℃.
[0059] According to an embodiment of the present invention, a thermal power unit 100 includes a biomass fuel preparation system 3.
[0060] According to an embodiment of the present invention, the thermal power unit 100 is equipped with a heat exchanger 33 having a first flow path 331 and a second flow path 332. The flue gas outlet of the biomass baking and carbonization equipment 32 is connected to the first flow path 331, and the second flow path 332 is connected to the air inlet pipe of the air preheater 2. The waste heat of the flue gas flowing out of the biomass baking and carbonization equipment 32 can be used to preheat the air about to enter the air preheater 2. Then, the flue gas flowing directly out of the coal-fired boiler 1 will be used to reheat the air in the air preheater 2. The heating effect of the air in the air preheater 2 is better. After the heated air in the air preheater 2 flows out, it can flow to the furnace of the coal-fired boiler 1. While assisting combustion, it helps to increase the temperature level in the furnace of the coal-fired boiler 1. The hot air can also accelerate the drying and ignition process of pulverized coal, making the combustion more stable and complete, and reducing the loss of incomplete combustion.
[0061] Other components and operations of the biomass fuel production system 3 according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.
[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions 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 one or more embodiments or examples.
[0063] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A biomass fuel production system, characterized in that, The biomass fuel preparation system is used in a thermal power unit, which includes a coal-fired boiler and an air preheater. The air preheater is connected to the flue gas outlet of the coal-fired boiler via a first pipeline. The biomass fuel preparation system includes: The first branch pipe, one end of which is connected to the first pipe; A biomass baking and carbonization device, wherein the biomass baking and carbonization device is provided with a receiving space for containing biomass materials, and the flue gas inlet of the biomass baking and carbonization device is connected to the other end of the first branch pipe; The heat exchanger has a first flow path and a second flow path. The flue gas outlet of the biomass baking and carbonization equipment is connected to the first flow path, and the second flow path is connected to the air inlet pipe of the air preheater.
2. The biomass fuel production system according to claim 1, characterized in that, The flue gas outlet of the biomass baking and carbonization equipment is connected to a first branch pipe, the heat exchanger is installed on the first branch pipe, and a first dust collector is installed on the first branch pipe, with the first dust collector located upstream of the heat exchanger.
3. The biomass fuel production system according to claim 2, characterized in that, The first branch pipe is equipped with a first regulating valve, which is located upstream of the first dust collector and is used to regulate the opening and closing of the first branch pipe and the flow rate of flue gas in the first branch pipe.
4. The biomass fuel production system according to claim 1, characterized in that, The flue gas outlet of the biomass baking and carbonization equipment is connected to a second branch pipe, which is connected to the dry slag removal system at the bottom of the coal-fired boiler.
5. The biomass fuel production system according to claim 4, characterized in that, The second branch pipe is equipped with a second regulating valve, which is used to regulate the opening and closing of the second branch pipe and the flow rate of flue gas in the second branch pipe.
6. The biomass fuel production system according to claim 1, characterized in that, The flue gas outlet of the biomass baking and carbonization equipment is connected to a third branch pipe, which is connected to the hot secondary air box of the coal-fired boiler.
7. The biomass fuel production system according to claim 6, characterized in that, The third branch pipe is equipped with a second dust collector and a third regulating valve. The third regulating valve is located upstream of the second dust collector and is used to regulate the opening and closing of the third branch pipe and the flue gas flow rate in the third branch pipe.
8. The biomass fuel production system according to claim 1, characterized in that, An extraction fan is provided on the first branch pipe. The extraction fan is used to guide the flue gas from the coal-fired boiler to the biomass baking and carbonization equipment. A fourth regulating valve is also provided upstream of the extraction fan. The fourth regulating valve is used to regulate the opening and closing of the first branch pipe and the flue gas flow rate in the first branch pipe.
9. The biomass fuel production system according to claim 1, characterized in that, The biomass roasting and carbonization equipment includes: The device body, wherein the accommodating space is located inside the device body; A feeding hopper, which is located on the upper side of the equipment body and communicates with the accommodating space; The discharge pipe is located on the lower side of the equipment body and communicates with the receiving space.
10. A thermal power unit, characterized in that, include: The biomass fuel preparation system according to any one of claims 1-9.