Novel low-carbon rapid load adjusting system and method for coal power unit

Abstract

The novel low-carbon rapid load adjusting system comprises a coal-fired boiler, a connector is formed in a high-temperature area of the coal-fired boiler and connected with a high-temperature boiler smoke flue, the other end of the high-temperature boiler smoke flue is connected to biomass treatment equipment, and the gas outlet side of the biomass treatment equipment is connected with a boiler smoke return flue. The flue gas is returned to the coal-fired boiler through the flue gas return flue; the other end of the biomass treatment equipment is connected with biomass intermediate product storage equipment through a biomass intermediate product conveying pipeline, and the biomass intermediate product storage equipment conveys generated biomass intermediate products to the coal-fired boiler through a conveying system for blending combustion. When the load of the unit is rapidly reduced, the boiler smoke is extracted, so that heat carried by a working medium on the steam turbine side is reduced, time is provided for slow load reduction of a boiler and an auxiliary machine, and the service life of the unit is prolonged; and when the load of the unit is rapidly increased, the generated biomass intermediate product is subjected to blending combustion, so that time is provided for the load increase of auxiliary machines such as a coal mill, and the functions of carbon reduction and rapid adjustment are achieved.

Description

Technical Field

[0001] This invention involves biomass co-firing and rapid load regulation for coal-fired units. It can be applied to new construction and retrofitting of existing units in response to next-generation coal-fired power technology. This invention maintains the conventional configuration of the coal-fired unit's auxiliary equipment, minimizing the impact on the service life of the boiler's heating surfaces while simultaneously addressing the challenges of clean carbon reduction and rapid load regulation for coal-fired units. Background Art

[0002] The new generation of coal-fired power generation technology is simultaneously demanding clean, carbon-reducing, and efficient regulation for coal-fired units. The limited load response rate of coal-fired unit pulverizing systems, coupled with the rapid stress changes on the boiler's heating surface during rapid load changes, which reduces boiler lifespan, are key factors hindering rapid load regulation. Large oil-fired boilers with similar parameters abroad have faster load regulation rates because their fuel supply systems respond more quickly than pulverized coal supply systems. For coal-fired units, receiving a load change command from the grid requires a significant amount of time to feed coal and adjust the pulverizer output to the grid's required load.

[0003] Biomass is a zero-carbon energy source. Blending biomass with coal-fired units is an important means of reducing carbon emissions. However, due to the wide range of biomass fuel sources and different moisture contents, and the long biomass fibers, crushing and transportation can easily cause blockages, resulting in unsatisfactory operation of current coal-fired unit biomass blending projects.

[0004] CN119844785 A discloses a low-load stable combustion and co-firing system and control method for a coupled pulverized coal boiler. This system utilizes the hot air from the boiler to gasify biomass, and the resulting fuel gas and some carbon are then fed into the boiler for combustion, achieving biomass co-firing. Because the heat source for biomass gasification comes from the boiler's hot air, the quality and calorific value of the biomass gasification product are affected by the boiler load and are started and stopped with the boiler. While this system's primary purpose is to achieve low-load stable combustion and co-firing by utilizing the biomass gasification product, it lacks the ability to rapidly adjust the load.

[0005] CN118344886A discloses a biochar production system and method for coal-fired power plants. This system extracts high-temperature boiler flue gas into a biochar production device, where it converts biomass raw materials into biochar. This invention primarily provides a biochar production method, but it lacks the ability to rapidly adjust the boiler's load or achieve carbon reduction through biomass co-combustion. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: how to achieve low-carbon combustion and rapid load adjustment of coal-fired units.

[0007] To solve the above problems, the present invention is achieved through the following technical solutions: A new type of low-carbon rapid load adjustment system for coal-fired power units includes a coal-fired boiler, an interface is opened in the high-temperature zone of the coal-fired boiler, the interface is connected to a high-temperature flue, the other end of the high-temperature flue is connected to a biomass processing device, the gas outlet side of the biomass processing device is connected to a flue return flue, and the flue gas is returned to the coal-fired boiler by the flue return flue; and the other end of the biomass processing device is connected to a biomass intermediate product storage device through a biomass intermediate product conveying pipeline, and the biomass intermediate product storage device conveys the generated biomass intermediate product to the coal-fired boiler for co-combustion through a conveying system.

[0008] The biomass processing equipment is a biomass oil preparation device. The gas outlet side of the biomass oil preparation device is connected to the flue gas return duct, and the flue gas is returned to the coal-fired boiler by the flue gas return duct; and the oil outlet side of the biomass oil preparation device is also connected to the biomass oil storage tank through a biomass intermediate product delivery pipeline, and the biomass oil storage tank also enters the coal-fired boiler through the boiler oil supply pipeline, so that the biomass oil enters the coal-fired boiler for mixed combustion.

[0009] A furnace smoke inserting plate door and a furnace smoke regulating door are arranged on the high-temperature furnace smoke duct; a return smoke duct regulating door and a return smoke duct inserting plate door are arranged on the furnace smoke return duct.

[0010] An oil pump and a regulating valve before the burner are provided on the oil supply pipeline to the boiler, and the end of the oil supply pipeline to the boiler extends to the oil gun of the coal-fired boiler; the burner of the coal-fired boiler enters the biomass oil storage tank through the return oil pipeline, and an oil return valve group is provided in the return oil pipeline.

[0011] The biomass processing equipment is a biomass carbon making and crushing device; the gas outlet side of the biomass carbon making and crushing device is connected to the flue gas return duct, and the flue gas is returned to the coal-fired boiler by the flue gas return duct; and the biomass carbon making and crushing device is connected to the biomass carbon silo through the biomass intermediate product conveying pipeline, and the biomass carbon output from the biomass carbon silo is sent to the coal-fired boiler through the powder feeder for co-combustion.

[0012] A smoke temperature regulating device and a smoke regulating door are provided on the high-temperature smoke duct; a return smoke duct regulating door is provided on the smoke return duct.

[0013] The biomass carbon bin is connected to the powder feeder through a biomass carbon drop pipe, and a biomass carbon gate is provided on the biomass carbon drop pipe.

[0014] The pulverizer is connected to the pulverized coal burner of the coal-fired boiler through the biomass carbon powder entering the furnace pipeline, and the secondary air is connected to the biomass carbon powder entering the furnace pipeline through the secondary air supply pipe, and a secondary air regulating damper is provided on the secondary air supply pipe.

[0015] A method for rapidly adjusting load of the system includes the following steps: Step 1: Open an interface in the high-temperature zone of the coal-fired boiler to lead out the high-temperature flue gas. When the unit needs to reduce the load quickly, the high-temperature flue gas of the coal-fired boiler is controlled to be led out along the high-temperature flue gas duct to the biomass processing equipment outside the boiler. The control method is as follows: when the power grid requires the load reduction to be completed within time t at a load reduction rate of a%Pe / min, the coal-fired boiler (1) reduces the load at a load reduction rate of 0.5a%Pe / min within time 2t, and the heat increase value of the flue gas leads increases at a rate of 0.5a%Pe / min from time 0 to time t, and the flue gas leads to the maximum at time t; from time t to 2t, the heat drawn from the flue gas decreases at a rate of 0.5a%Pe / min, and the flue gas leads are stopped at time 2t; at this time, the unit has reached the output required by the power grid at time t, and the output of the unit remains unchanged within the range from time t to 2t. The boiler completes the load reduction within time 2t and reaches the output required by the power grid.

[0016] Compared with existing technologies, this invention offers the following advantages: During rapid load shedding, high-temperature flue gas (approximately 600°C to 800°C, depending on boiler load) is extracted from the furnace and fed into the biomass processing equipment. The biomass undergoes rapid cracking at high temperatures, generating biooil / biochar, which is then transported and stored via pipelines. During this period, the load on the boiler and auxiliary equipment slowly decreases. The removal of some flue gas reduces the heat on the steam side, enabling rapid load reduction. During rapid load increase, auxiliary equipment such as the coal mill has a limited response rate. Biomass intermediates are then fed into the coal-fired boiler for co-combustion, rapidly increasing the total calorific value of the fuel entering the boiler and assisting the boiler in rapidly increasing the unit's load.

[0017] During rapid load reduction, this invention extracts flue gas, reducing the heat carried by the working fluid on the turbine side. This allows time for the boiler and auxiliary equipment to ramp down, extending the unit's lifespan. During rapid load increase, the generated biomass intermediates are co-combusted, allowing time for auxiliary equipment such as the coal mill to ramp up, achieving carbon reduction and rapid load regulation. This invention addresses the challenges of clean carbon reduction and rapid load change for newly built coal-fired units. It also reduces carbon emissions and improves load response rates for existing units without changing their auxiliary equipment configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural diagram of Example 1 of the present invention; Figure 2 This is a structural diagram of Example 2 of the present invention; Figure 3 This is a schematic diagram of rapid load reduction when the load is above 50%; Figure 4 This is a schematic diagram of rapid load reduction below 50% load; Figure 5 This is a schematic diagram of rapid load increase above 50% load; Figure 6 This is a schematic diagram of rapid load increase below 50% load. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0021] A novel low-carbon, rapid load adjustment system for coal-fired power units includes a coal-fired boiler 1. A port is opened in the high-temperature zone of the coal-fired boiler 1, connected to a high-temperature flue 101. The other end of the high-temperature flue 101 is connected to a biomass processing device. The gas outlet of the biomass processing device is connected to a flue return 102, which returns the flue gas to the coal-fired boiler 1. The other end of the biomass processing device is connected to a biomass intermediate product storage device via a biomass intermediate product delivery pipeline 103. The biomass intermediate product storage device delivers the generated biomass intermediate product to the coal-fired boiler 1 for co-combustion via a delivery system.

[0022] The biomass processing equipment is a biomass oil preparation device 41 or a biomass charcoal making and crushing device 42 .

[0023] Example 1 like Figure 1 As shown, a novel low-carbon, rapid load adjustment system for coal-fired power units includes a coal-fired boiler 1. A port is opened in the high-temperature zone of the coal-fired boiler 1, connected to a high-temperature flue duct 101. The other end of the high-temperature flue duct 101 is connected to a biomass oil production device 41. The gas outlet of the biomass oil production device 41 is connected to a flue return duct 102, which returns the flue gas to the coal-fired boiler 1. Furthermore, the oil outlet of the biomass oil production device 41 is connected to a biomass oil storage tank 7 via a biomass intermediate product delivery pipeline 103. The biomass oil storage tank 7 then enters the coal-fired boiler 1 via a boiler oil supply pipeline 104, allowing the biomass oil to enter the coal-fired boiler 1 for co-combustion.

[0024] It should be noted that the biomass intermediate product delivery pipeline 103 here is a biomass oil delivery pipeline.

[0025] Furthermore, a furnace smoke inserting door 2 and a furnace smoke regulating door 3 are provided on the high-temperature furnace smoke duct 101 .

[0026] Furthermore, a return flue regulating door 5 and a return flue plug-in door 6 are provided on the furnace smoke return flue 102 .

[0027] Furthermore, an oil pump 8 and a regulating valve 9 before the burner are provided on the oil supply pipe 104 to the boiler, and the end of the oil supply pipe 104 to the boiler extends to the burner such as the oil gun 11 of the coal-fired boiler 1 .

[0028] Furthermore, the burner of the coal-fired boiler 1 enters the biomass oil storage tank 7 through the return oil pipeline 105, and an oil return valve group 10 is provided in the return oil pipeline.

[0029] The working principle of Example 1 is: The operating principle of this invention is that when the coal-fired boiler 1 is deloaded, high-temperature flue gas is extracted. The heat is quickly dissipated to the turbine working medium, enabling the unit to rapidly deload. The extracted high-temperature flue gas is then used to produce biomass oil. When the unit is loaded up, the zero-carbon biooil enters the boiler within seconds, assisting in rapidly increasing the unit's load. Specifically, an interface is opened in the high-temperature zone of the coal-fired boiler 1 to lead out the high-temperature flue gas. When the unit needs to reduce the load quickly, the flue gas plug-in door 2, the flue gas regulating door 3, the return flue gas regulating door 5 and the return flue gas plug-in door 6 are opened to control the high-temperature flue gas of the coal-fired boiler 1 to be led out along the high-temperature flue gas duct 101 to the biomass oil preparation device 41 outside the boiler. Due to the extraction of the flue gas, when the load of the coal-fired boiler 1 remains unchanged or slowly decreases, the heat absorption of the working medium on the steam turbine side is immediately reduced, so that the unit can complete the rapid load reduction. During the process of reducing the load of the coal-fired boiler 1, the flue gas regulating door 3, the flue gas plug-in door 2, the return flue gas regulating door 5 and the return flue gas plug-in door 6 are gradually closed. When the coal-fired boiler 1 is reduced to the load required by the power grid, the flue gas regulating door 3, the flue gas plug-in door 2, the return flue gas regulating door 5 and the return flue gas plug-in door 6 are completely closed. At this point, the unit completes the rapid load reduction.

[0030] The biomass oil produced by the biomass oil production device 41 is stored in the biomass oil storage tank 7 via the biomass delivery pipeline 103. The biomass oil storage tank 7 is equipped with a boiler oil supply pipeline 104, an oil pump 8, a pre-burner regulating valve 9, an oil return pipeline 105, and an oil return valve assembly 10. During normal operation, the oil return valve assembly 10 is fully open, and the oil pump 8 and the boiler oil supply pipeline 104 are in hot standby mode. In other words, the pre-burner regulating valve 9 and the oil return valve assembly 10 are open. Fuel is delivered from the outlet of the oil pump 8, passes through the pre-burner regulating valve 9, and returns to the biomass oil storage tank 7 through the oil return valve assembly 10 and the oil return pipeline 105 before entering the oil gun 11.

[0031] When the unit rapidly increases its load, under the premise of ensuring the safety of furnace combustion, the opening of the return oil valve group 10 is reduced to control the flow of biomass oil entering the oil gun 11 by reducing the return oil volume. Biomass oil has a high calorific value and can enter the furnace through the oil gun for combustion within seconds, assisting the unit in achieving rapid load increase. Since biomass is a zero-carbon fuel, burning biomass oil can enable the unit to meet the requirements of clean carbon reduction. As the load of auxiliary equipment and coal-fired boiler 1 increases, the unit gradually reaches the load required by the power grid. At this time, the opening of the return oil valve group 10 is gradually increased to increase the return oil volume of biomass oil. The biomass oil supply pipeline 104 and the return oil pipeline 105 enter the hot standby state again. At this point, the unit completes rapid load increase.

[0032] A novel low-carbon rapid load adjustment method for coal-fired power units comprises the following steps: Step 1: Open an interface in the high-temperature area of the coal-fired boiler 1 to lead out the high-temperature flue gas. When the unit needs to reduce the load quickly, open the flue gas plug door 2, the flue gas regulating door 3, the return flue gas regulating door 5 and the return flue gas plug door 6 to control the high-temperature flue gas of the coal-fired boiler 1 to be led out along the high-temperature flue gas duct 101 to the biomass oil preparation device 41 outside the boiler. Due to the extraction of the flue gas, when the load of the coal-fired boiler 1 remains unchanged or slowly decreases, the heat absorption of the working medium on the steam turbine side is immediately reduced, so that the unit can complete the rapid load reduction. In the process of reducing the load of the boiler 1, gradually close the flue gas regulating door 3, the flue gas plug door 2, the return flue gas regulating door 5, and the return flue gas plug door 6. When the boiler 1 drops to the load required by the power grid, completely close the flue gas regulating door 3, the flue gas plug door 2 and the return flue gas regulating door 5 and the return flue gas plug door 6. At this point, the unit completes the rapid load reduction. The specific control method is: When the power grid requires a load reduction rate of a%Pe / min within time t, the boiler de-loads at a rate of 0.5a%Pe / min within time 2t. The heat added by flue gas extraction increases at a rate of 0.5a%Pe / min from time 0 to time t, reaching its maximum at time t. From time t to 2t, the heat added by flue gas decreases at a rate of 0.5a%Pe / min, and flue gas extraction ceases at time 2t. At this point, the unit has reached the power grid's output requirement at time t. The unit's output remains unchanged from time t to 2t, and the boiler completes its load reduction within time 2t, reaching the power grid's output requirement.

[0033] The heat Q removed from the smoke after completing a load reduction is: Q: Total heat removed from flue gas during a load reduction, MWh; a% Pe: load reduction rate of the power grid, MW / min; t: the time required by the power grid to complete load reduction, min; Boiler efficiency during load reduction; pipeline efficiency; Turbogenerator thermal efficiency during load reduction; Step 2: The biomass oil is stored in the biomass oil storage tank 7 through the delivery pipeline 103. The biomass oil storage tank 7 is provided with a boiler oil supply pipeline 104, an oil pump 8, a burner front regulating valve 9, an oil return pipeline 105 and an oil return valve group 10. When the unit is operating normally, the oil return valve group 10 is fully open, the oil pump 8 and the boiler oil supply pipeline 104 are in a hot standby state, that is, the burner front regulating valve 9 and the oil return valve group 10 are in an open state, and the fuel is sent out from the outlet of the oil pump 8, passes through the burner front regulating valve 9, and returns to the biomass oil storage tank 7 through the oil return valve group 10 and the oil return pipeline 105 before entering the oil gun 11.

[0034] The specific control method is as follows: when the power grid requires a load increase rate of a%Pe / min within time t, the boiler increases its load at a rate of 0.5a%Pe / min within time 2t. The added heat value of the biomass oil increases at a rate of 0.5a%Pe / min from time 0 to time t, reaching its maximum biomass oil input at time t. From time t to 2t, the added heat value of the biomass oil decreases at a rate of 0.5a%Pe / min, and the biomass oil input is stopped at time 2t. At this point, the unit has reached the power grid's output requirement at time t. The unit's output remains unchanged from time t to 2t, and the boiler completes its load increase within time 2t, reaching the power grid's output requirement.

[0035] The heat Q' (MWh) of biomass oil input to complete one load increase is Furthermore, when the unit rapidly increases its load, under the premise of ensuring the safety of furnace combustion, the opening of the return oil valve group 10 is reduced to control the flow of biomass oil entering the oil gun 11 by reducing the return oil volume. Biomass oil has a high calorific value and can enter the furnace through the oil gun for combustion within seconds, assisting the unit in achieving rapid load increase. Since biomass is a zero-carbon fuel, burning biomass oil can enable the unit to meet the requirements of clean carbon reduction. As the load of auxiliary equipment and coal-fired boiler 1 increases, the unit gradually reaches the load required by the power grid. At this time, the opening of the return oil valve group 10 is gradually increased, increasing the return oil volume of biomass oil, and the biomass oil supply pipeline 104 and return oil pipeline 105 enter the hot standby state again. At this point, the unit completes rapid load increase.

[0036] This embodiment extracts high-temperature flue gas during load reduction of the coal-fired boiler, directly reducing the heat of the steam-side working medium and achieving rapid load reduction of the thermal power unit. This also buys time for the boiler and auxiliary equipment to reduce load, extending equipment life. The extracted flue gas is used to produce biomass oil. As a zero-carbon, high-calorie fuel, biomass oil can be injected into the furnace through the boiler oil nozzle within seconds during rapid load increase, achieving the goal of clean carbon reduction while rapidly increasing the load of the auxiliary unit. This invention solves the problems of clean carbon reduction and rapid load change for newly built coal-fired units, while achieving carbon reduction and improving load response rate for existing units without changing the auxiliary equipment configuration of the existing units.

[0037] The present invention encompasses all scenarios involving extracting boiler flue gas to process biomass, and regulating boiler load by controlling the ratio of extracted flue gas and the amount of biomass intermediate products used. For example, extracting flue gas to produce biochar can be used to co-combust the biochar into the boiler as needed to increase boiler load (including scenarios where the biochar is ground in a coal mill or ground separately and fed into a separate burner). Another example involves extracting flue gas to gasify biomass, storing the gasification products, and using them to regulate boiler load according to variable boiler load conditions. The present invention also encompasses various scenarios involving uniform and non-uniform variable load regulation.

[0038] According to the new requirements, the ramping speed (load-changing capacity) of coal-fired power units depends on factors such as unit type and load factor. For subcritical units above 50% load, the load-changing capacity is 1.5%Pe / min (Pe is rated power) to 2.5%Pe / min, and for ultra-supercritical units, it is 1.3%Pe / min to 2.2%Pe / min. For 40% to 50% load, the load-changing capacity is 1.2%Pe / min, and for 30% to 40% load, the load-changing capacity is 1.0%Pe / min. The next-generation coal-fired power generation technology requires a load-changing rate of at least 2.2%Pe / min for new units above 50% load, with demonstration units achieving at least 4%Pe / min. For 30% to 50% load, the load-changing rate is at least 1%Pe / min, with demonstration units achieving at least 2%Pe / min. The boiler load-changing rate is primarily limited by the response speed of boiler auxiliary equipment (such as the pulverizer).

[0039] The present invention enables the auxiliary unit to achieve rapid load change without changing the configuration of the boiler and the auxiliary machine.

[0040] Assume that the coal-fired boiler 1 is a 660MW coal-fired power generation unit, and has a load increase and decrease capability of 2%Pe / min above 50% load, and a load increase and decrease capability of 1%Pe / min below 50% load.

[0041] (1) Rapid load reduction above 50% When the grid dispatching agency issues an AGC instruction to the thermal power plant to quickly reduce the load (for example, reducing the load from 80% Pe to 60% Pe within 5 minutes at 4% Pe% / min), the flue gas plug-in door 2 and the return flue gas plug-in door 6 are opened, and the flue gas regulating door 3 and the return flue gas regulating door 5 are gradually opened. The flue gas is drawn along the high-temperature flue gas duct 101 and enters the biomass oil preparation device 41. The generated biomass oil is stored in the biomass oil storage tank 7. The low-temperature flue gas, after the waste heat has been utilized, returns to the tail end of the coal-fired boiler 1 along the flue gas return flue duct 102.

[0042] The total heat of the flue gas extracted during this load reduction is Q1 = 2%Pe·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 (MWh).

[0043] Assume η 锅 is 0.93, η 管 is 0.98, η 汽 =0.40, the total heat of the flue gas extracted during this load reduction is Q1=2%·660·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 =15.09 (MWh).

[0044] from Figure 3 It can be seen that the boiler reached the load required by the power grid at a load reduction rate of 2%Pe / min in the 10th minute, reducing the load from 80% to 60%. The opening of the flue gas regulating door reached its maximum in the 5th minute and then gradually decreased. The unit met the load reduction requirements of the power grid in the 5th minute, and the boiler and auxiliary equipment maintained the existing load reduction rate unchanged. Due to the removal of flue gas, the input heat of the unit was reduced, and the load reduction rate of the unit doubled.

[0045] (2) Rapid load reduction below 50% load Load reduction below 50% load: When receiving a load reduction instruction from the power grid (for example: increasing the load from 50% to 40% within 5 minutes at 2%Pe% / min).

[0046] The total heat of the flue gas extracted during this load reduction is Q2 = 1%Pe·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 (MWh).

[0047] Assume η 锅 is 0.92, η 管 is 0.95, η 汽 =0.38, the total heat of the flue gas extracted during this load reduction is Q2=1%·660·5·10 / 60·1 / 2 / η锅 / η 管 / η 汽 =8.28 (MWh). Depend on Figure 4 It can be seen that the boiler and auxiliary equipment reduced their load from 50% to 40% at a load reduction rate of 1%Pe / min in the 10th minute, and the opening of the flue gas regulating door 3 reached its maximum in the 5th minute and then gradually decreased; the unit reached 40% load within the 5th minute, that is, when the load reduction rate of the boiler and auxiliary equipment remained unchanged, the flue gas extraction auxiliary unit completed a rapid load reduction.

[0048] When the unit reaches the load required by the power grid, the furnace smoke regulating door 3, the furnace smoke plug-in door 2, the return flue regulating door 5 and the return flue plug-in door 6 are closed, and the unit returns to a stable operating state.

[0049] The smoke insert door 2 and the return flue regulating door 5 can both use electric or pneumatic actuators, and the operation can be started within a few seconds or tens of seconds, thereby increasing the load reduction rate of the unit. The extracted smoke enters the biomass oil production device, and the biomass is rapidly cracked in the absence of oxygen to form biomass oil. At this temperature, the oil yield of biomass oil is relatively high, mostly above 50%. The biomass oil has high fluidity and high calorific value, and can be stored in the biomass oil storage tank 7 after cooling; the combustible gas generated during the biomass cracking process can enter the oil production device to provide heat for cracking and oil production. The biomass oil generated by the biomass oil preparation device 41 enters the biomass oil storage tank for storage through the biomass conveying pipeline 103.

[0050] An oil supply pump 8 is provided at the outlet of the biomass oil storage tank 7. The oil pump 8 is connected to the boiler oil gun 11 through the boiler oil supply pipeline 104. A burner pre-regulating valve 9 is provided in front of the oil gun 11. When the boiler is running smoothly, the oil pump is in hot standby state (the pump is running, but not at full capacity). At this time, the return oil valve group 10 is fully open, and all the biomass oil returns to the biomass oil storage tank 7 through the return oil valve group 10.

[0051] (3) Rapid load increase above 50% load When the grid dispatching agency issues an AGC command to the thermal power plant to quickly increase the load (for example, increasing the load from 60% to 75% within 5 minutes at 3%Pe% / min), the opening of the return oil valve group is adjusted to adjust the amount of biomass oil entering the boiler oil gun.

[0052] The total heat of biomass oil fed in this load increase is Q3 = 1.5%Pe·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 (MWh).

[0053] Assume η 锅 is 0.93, η管 is 0.98, η 汽 =0.40, the total heat of biomass oil fed in this load increase is Q3=1.5%·660·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 =11.32 (MWh). Depend on Figure 5 It can be seen that by maintaining the boiler's load increase rate at 1.5%Pe / min, the boiler reaches the grid's required load factor in the 10th minute, and the oil nozzle reaches its maximum output in the 5th minute, then gradually decreases, and the oil nozzle is completely disconnected at the 10th minute. At the 5th minute, the unit's output power reaches the grid's required load, and the boiler stops increasing its load, entering a stable operation state. While maintaining the same load increase rate for the boiler and auxiliary equipment, the use of biomass oil doubles the unit's load increase rate.

[0054] (4) Rapid load increase below 50% load When the power grid issues a rapid load increase command (for example, increasing the load from 40% to 50% within 5 minutes at 2%Pe% / min), the opening of the oil return valve group is reduced to increase the amount of biomass oil entering the boiler oil gun.

[0055] Depend on Figure 6 As can be seen, the boiler maintained a load increase rate of 1%Pe / min, reaching the grid's required load factor in the 10th minute. Biomass oil began to be used upon receiving the grid's command, reaching maximum output in the 5th minute, then gradually decreasing until the oil nozzle was removed in the 10th minute. The unit had already reached the grid's required load factor in the 5th minute. At the end of the 10th minute, both the boiler and the unit had reached the grid's required load, and the boiler entered stable operation. While maintaining the same load increase rate for the boiler and auxiliary equipment, the use of biomass oil doubled the unit's load increase rate.

[0056] The total heat of biomass oil fed in this load increase is Q4 = 1%Pe·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 (MWh).

[0057] Assume η 锅 is 0.92, η 管 is 0.95, η 汽 =0.38, the total heat of biomass oil fed in this load increase is Q4=1%·660·5·10 / 60·1 / 2 / η 锅 / η 管 / η 汽 =8.28 (MWh). When the unit is under low load, biomass oil can also be used to stabilize combustion or support combustion. When the boiler is rapidly de-loaded, the heat from the flue gas is extracted and used to produce biomass oil, achieving energy conversion and storage. When the boiler is rapidly loaded, the biomass oil is put into use and burned in the furnace, completing the process of biomass feedstock entering the plant and then being mixed with the furnace. Biomass is a zero-carbon fuel. This invention not only enables rapid load adjustment of the unit, but also reduces the unit's carbon emissions.

[0058] Example 2 like Figure 2 As shown, a flue gas charcoal making and unit rapid load adjustment system includes a coal-fired boiler 1. A port is opened in the high-temperature zone of the coal-fired boiler 1. The port is connected to a high-temperature flue gas duct 101. The other end of the high-temperature flue gas duct 101 is connected to a biomass charcoal making and pulverizing device 42. The gas outlet of the biomass charcoal making and pulverizing device 42 is connected to a flue gas return duct 102, which returns the flue gas to the coal-fired boiler 1. Furthermore, the biomass charcoal making and pulverizing device 42 is connected to a biochar silo 12 via a biochar delivery pipeline 103. The biochar output from the biochar silo 12 is delivered to the coal-fired boiler 1 via a pulverizer 14 for co-combustion.

[0059] It should be noted that the biomass intermediate product conveying pipeline 103 here is a biomass charcoal conveying belt.

[0060] Furthermore, a smoke temperature regulating device 13 , a smoke regulating door 3 and a smoke inserting door 2 are provided on the high-temperature smoke duct 101 .

[0061] Furthermore, a return flue regulating door 5 and a return flue plug-in door 6 are provided on the furnace smoke return flue 102 .

[0062] Furthermore, the biomass carbon bin 12 is connected to the powder feeder 14 via a biomass carbon drop pipe 106 , and a biomass carbon gate 15 is provided on the biomass carbon drop pipe 106 .

[0063] Furthermore, the powder feeder 14 is connected to the pulverized coal burner 16 of the coal-fired boiler 1 through the biomass pulverized coal pipe 107 entering the furnace, and the secondary air is connected to the biomass pulverized coal pipe 107 entering the furnace through the secondary air supply pipe 108, and a secondary air regulating damper 17 is provided on the secondary air supply pipe 108.

[0064] When the power grid requires a coal-fired unit to rapidly reduce its load, the flue gas control door 3 is opened, allowing a portion of the boiler flue gas to enter the biomass charcoal making and pulverization unit 42 through the high-temperature flue gas duct 101, serving as the heat source for biomass pyrolysis and charcoal production. The biomass charcoal making and pulverization unit 42 utilizes a mature biomass charcoal production process. Existing processes typically use high-temperature flue gas generated by natural gas combustion as the heat source, producing biochar through drying, cracking, and carbonization at temperatures between 300°C and 600°C (depending on the reaction temperature of different biomasses). The heat source in this embodiment utilizes high-temperature flue gas from coal-fired boilers. The temperature of the extracted flue gas can be controlled by the flue gas temperature control device 13, a steam heater that controls the steam flow rate and, therefore, the extracted flue gas temperature. After heat exchange, the furnace flue gas enters the boiler tail through the flue gas return duct 102, where it enters the next flue gas purification process along with the tail flue gas. The biochar produced by the biomass charcoal making and pulverization unit 42 is crushed to the required particle size and then transported by a biochar conveyor belt to the biochar silo 12 for storage. At this point, the boiler and auxiliary equipment loads remain unchanged (or slowly decrease), while the heat of the working medium on the steam side decreases, allowing the auxiliary units to achieve rapid load reduction. As the boiler and auxiliary equipment loads decrease, the flue gas damper 3 gradually closes, thus achieving the system's function of rapidly reducing the auxiliary units' loads.

[0065] When the power grid requires the coal-fired units to increase their load quickly, the pulverizing system cannot increase its output immediately in a short period of time due to the hysteresis in its response. At this time, the biochar gate 15 is opened, and according to the requirements of the boiler's variable load rate, biochar is supplied to the pulverizer. The secondary air damper 17 is opened, and the biochar powder is sent to the independently set pulverized coal burner 16 by the secondary air. Since biochar has a high calorific value, generally between 20MJ / kg and 30MJ / kg, the independently set pulverized coal burner 16 is conducive to air distribution and full combustion. At this time, when the pulverizer load does not change, it is equivalent to adding a high-calorific value zero-carbon fuel. The calorific value of the fuel entering the furnace increases, assisting the boiler to achieve a rapid load increase and realizing the function of clean carbon reduction.

[0066] A novel low-carbon rapid load adjustment method for coal-fired power units comprises the following steps: Step 1: Flue gas is extracted from the tail flue of coal-fired boiler 1. When the power grid requires rapid load reduction of the coal-fired unit, flue gas regulating gate 3 is opened. A portion of the flue gas from coal-fired boiler 1 enters the biomass charcoal production and pulverization device 42 through the high-temperature flue gas duct 101, serving as a heat source for biomass pyrolysis and charcoal production. Flue gas regulating gate 3 gradually closes, thus enabling the system to assist the unit in achieving rapid load reduction. The specific control method is as follows: When the power grid requires load reduction at a rate of a%Pe / min within time t, coal-fired boiler 1 is deloaded at a rate of 0.5%Pe / min within time 2t. The heat gain from flue gas increases at a rate of 0.5%Pe / min from time 0 to time t, reaching its maximum at time t. From time t to time 2t, the heat gain from flue gas decreases at a rate of 0.5%Pe / min, and flue gas extraction ceases at time 2t. At this time, the unit has reached the output required by the grid at time t, and the unit's output remains unchanged within the range of time t to 2t. The boiler completes load reduction within time 2t and reaches the output required by the grid.

[0067] Step 2: When the power grid requires a rapid load increase for the coal-fired unit, due to the hysteresis in the pulverizer's response, the biochar gate 15 under the biochar bin 12 is opened. Based on the variable load rate required by the coal-fired boiler 1, biochar is supplied to the pulverizer 14. The secondary air damper 17 is opened, and the secondary air flows the biochar pulverized coal to the independently installed pulverized coal burner 16. At this point, while the pulverizer load remains unchanged, the addition of high-calorific-value, zero-carbon fuel is equivalent to increasing the calorific value of the incoming fuel, assisting the coal-fired boiler 1 in achieving rapid load increase and achieving clean, carbon-reducing performance. The specific control method is as follows: when the power grid requires a load increase rate of a%Pe / min within time t, the boiler increases its load at a rate of 0.5a%Pe / min within time 2t. The added heat value of the biochar increases at a rate of 0.5a%Pe / min from time 0 to time t, reaching its maximum biochar input at time t. From time t to 2t, the added heat value of the biochar decreases at a rate of 0.5a%Pe / min, and the biochar input is stopped at time 2t. At this point, the unit has reached the power grid's output requirement at time t, and the unit's output remains unchanged from time t to 2t. Coal-fired boiler 1 completes its load increase within time 2t, reaching the power grid's output requirement.

[0068] In this embodiment 2, biochar is mixed and burned when the unit is increasing its load, which increases the calorific value of the fuel entering the furnace during the time when the auxiliary equipment increases its load, and at the same time achieves the purpose of clean carbon reduction. When the unit is reducing its load, the furnace smoke is extracted and led out of the furnace, and the excess furnace smoke is used to produce biochar. While the unit meets the requirements of rapid load change of the power grid, the load reduction time of the boiler and auxiliary equipment is extended, thereby extending the life of the boiler and auxiliary equipment. This embodiment simultaneously achieves clean carbon reduction and rapid load adjustment of the unit, and achieves rapid load adjustment without changing the configuration of the auxiliary equipment and minimizing the impact on the life of the boiler and auxiliary equipment. The present invention will solve the difficult problems of clean carbon reduction and rapid load change of newly built coal-fired units, and at the same time achieve carbon reduction and improved load response rate of existing units without changing the auxiliary equipment configuration of existing units.

[0069] Compared with the prior art, the present invention has the following beneficial effects: 1. Relative to CN119844785 A: ① The present invention extracts high-temperature boiler smoke, and CN119844785 A uses hot air; ② The present invention uses furnace smoke to produce biomass oil when the boiler is under load, while CN119844785 A uses hot air to gasify biomass, and the products are mainly fuel gas and a small amount of biomass charcoal; ③. When the boiler is deloaded, the present invention converts excess heat from the boiler into high-calorific-value biomass oil and stores it. When the boiler is loaded, the biomass oil is used to quickly increase the boiler's heat. This allows the unit to quickly adjust its load while maintaining the same boiler and auxiliary equipment configurations and the existing load adjustment rate. At the same time, it allows biomass to enter the plant, enter the furnace, and be mixed and burned to reduce carbon emissions. The output of the biomass gasification device in CN119844785 A changes with the boiler load, and cannot achieve the load adjustment function.

[0070] 2. Relative to CN118344886A ① Although the present invention introduces high-temperature furnace smoke, the purpose is to assist in reducing the boiler load, and the furnace smoke enters the biomass oil production device, and the main product is biomass oil, which is different from the biomass charcoal produced by CN118344886A; ② The biomass oil of the present invention enters the boiler again for combustion when the boiler is loaded. CN118344886A only realizes the function of using the flue gas of a coal-fired boiler to produce biomass charcoal, without the step of mixing the oil into the boiler; ③. When the boiler is de-loaded, the present invention converts the excess heat of the boiler into high-calorific-value biomass oil and stores it. When the boiler is loaded, the biomass oil is used to quickly increase the heat of the boiler, thereby achieving the function of rapid load adjustment of the unit while keeping the boiler and auxiliary equipment configurations unchanged and the existing load adjustment rate unchanged. At the same time, the function of biomass entering the plant, entering the furnace, and co-combustion to reduce carbon emissions is achieved. CN118344886A cannot achieve the above functions.

[0071] In summary, this patent application is creative compared to the prior art.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. A new low-carbon rapid load adjustment system for coal-fired power units, characterized by: The invention comprises a coal-fired boiler (1), an interface is opened in the high-temperature zone of the coal-fired boiler (1), the interface is connected to a high-temperature flue (101), the other end of the high-temperature flue (101) is connected to a biomass processing device, the gas outlet side of the biomass processing device is connected to a flue return flue (102), and the flue gas is returned to the coal-fired boiler (1) by the flue return flue; and the other end of the biomass processing device is connected to a biomass intermediate product storage device through a biomass intermediate product delivery pipeline (103), and the biomass intermediate product storage device delivers the generated biomass intermediate product to the coal-fired boiler (1) through a delivery system for mixed combustion.

2. A novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 1, characterized in that: The biomass processing equipment is a biomass oil preparation device (41). The gas outlet side of the biomass oil preparation device (41) is connected to a flue gas return duct (102), and the flue gas is returned to the coal-fired boiler (1) through the flue gas return duct; and the oil outlet side of the biomass oil preparation device (41) is also connected to a biomass oil storage tank (7) through a biomass intermediate product delivery pipeline (103), and the biomass oil storage tank (7) also enters the coal-fired boiler (1) through a boiler oil supply pipeline (104), so that the biomass oil enters the coal-fired boiler (1) for mixed combustion.

3. A novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 2, characterized in that: A furnace smoke inserting plate door (2) and a furnace smoke regulating door (3) are provided on the high-temperature furnace smoke duct (101); and a return smoke duct regulating door (5) and a return smoke duct inserting plate door (6) are provided on the furnace smoke return duct (102).

4. A novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 2, characterized in that: An oil pump (8) and a regulating valve (9) before the burner are provided on the oil supply pipe (104) to the boiler. The end of the oil supply pipe (104) to the boiler extends to the oil gun (11) of the coal-fired boiler (1). The burner of the coal-fired boiler (1) enters the biomass oil storage tank (7) through the return oil pipe (105), and an oil return valve group (10) is provided in the return oil pipe.

5. The novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 1 is characterized by: The biomass processing equipment is a biomass carbon making and crushing device (42); the gas outlet side of the biomass carbon making and crushing device (42) is connected to the flue gas return flue (102), and the flue gas is returned to the coal-fired boiler (1) by the flue gas return flue; and the biomass carbon making and crushing device (42) is connected to the biomass carbon silo (12) through the biomass intermediate product conveying pipeline (103), and the biomass carbon output from the biomass carbon silo (12) is sent to the coal-fired boiler (1) through the powder feeder (14) for mixed combustion.

6. A novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 5, characterized in that: A smoke temperature regulating device (13) and a smoke regulating door (3) are provided on the high-temperature smoke duct (101); and a return smoke duct regulating door (5) is provided on the smoke return duct (102).

7. The novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 5 is characterized by: The biomass carbon bin (12) is connected to the powder feeder (14) via a biomass carbon drop pipe (106), and a biomass carbon gate (15) is provided on the biomass carbon drop pipe (106).

8. The novel low-carbon rapid load adjustment system for coal-fired power generation units according to claim 5 is characterized by: The pulverizer (14) is connected to the pulverized coal burner (16) of the coal-fired boiler (1) through the biomass carbon powder feeding pipe (107), and the secondary air is connected to the biomass carbon powder feeding pipe (107) through the secondary air supply pipe (108), and a secondary air regulating damper (17) is provided on the secondary air supply pipe (108).

9. A method for rapid load adjustment of the system according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: Open an interface in the high-temperature zone of the coal-fired boiler (1) to lead out the high-temperature flue gas. When the unit needs to reduce the load quickly, the high-temperature flue gas of the coal-fired boiler (1) is controlled to be led out along the high-temperature flue gas duct (101) to the biomass processing equipment outside the boiler. The control method is as follows: when the power grid requires the load reduction to be completed within time t at a load reduction rate of a%Pe / min, the coal-fired boiler (1) reduces the load at a load reduction rate of 0.5a%Pe / min within time 2t, and the heat increase value drawn out of the flue gas increases at a rate of 0.5a%Pe / min from time 0 to time t, and the flue gas extraction amount reaches the maximum at time t; from time t to 2t, the heat drawn out of the flue gas decreases at a rate of 0.5a%Pe / min, and the flue gas extraction is stopped at time 2t; at this time, the unit has reached the output required by the power grid at time t, and the output of the unit remains unchanged within the range from time t to 2t. The boiler completes the load reduction within time 2t and reaches the output required by the power grid; The heat Q removed from the smoke after completing a load reduction is: Q: Total heat removed from flue gas during a load reduction, MWh; a% Pe: load reduction rate of the power grid, MW / min; t: the time required by the power grid to complete load reduction, min; Boiler efficiency during load reduction; pipeline efficiency; Turbogenerator thermal efficiency during load reduction; Step 2: The other end of the biomass processing equipment is connected to the biomass storage equipment through the biomass conveying pipeline (103), and the biomass storage equipment conveys the generated biomass to the coal-fired boiler (1) through the conveying system for mixed combustion; the control method is: when the power grid requires the load to be increased at a load increase rate of a%Pe / min within time t, the pulverizing system of the coal-fired boiler (1) increases the load at a load increase rate of 0.5a%Pe / min within time 2t, and the heat increase value of the input biomass intermediate product increases at a rate of 0.5a%Pe / min from time 0 to time t, and the input amount of the biomass intermediate product reaches the maximum at time t; from time t to 2t, the heat of the input biomass intermediate product decreases at a rate of 0.5a%Pe / min, and the input of the biomass intermediate product is stopped at time 2t; at this time, the unit has reached the output required by the power grid at time t, and the output of the unit remains unchanged within the range from time t to 2t, and the pulverizing system of the boiler completes the load increase within time 2t to reach the output required by the power grid; The heat Q' (MWh) of biomass input to complete a load increase is 。

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