Biomass coupling pulverized coal fuel system and control method thereof

Abstract

The embodiment of the invention discloses a biomass coupling pulverized coal fuel system and a control method thereof. The biomass coupling pulverized coal fuel system comprises a biomass powder bin, a coal mill, a first conveying pipeline, a second conveying pipeline, a first branch, a second branch and a hearth. The biomass powder bin is used for feeding biomass powder into the second conveying pipeline through the first conveying pipeline and the first branch when the load of the biomass coupling pulverized coal fuel system is smaller than the preset load, and the biomass powder and pulverized coal produced by the coal mill are mixed and then enter the hearth together. The biomass powder bin is further used for feeding biomass powder into the hearth through the first conveying pipeline and the second branch when the load of the biomass coupling pulverized coal fuel system is larger than or equal to the preset load. And meanwhile, the coal mill is used for conveying the produced coal powder into the hearth through a second conveying pipeline. According to the technical scheme, the fuel system for coupling the biomass with the pulverized coal is arranged, the stable combustion capacity of the system in a low load state is improved, and the system performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel systems, and in particular to a biomass-coupled coal powder fuel system and a control method thereof. Background Art

[0002] With the continuous expansion of installed capacity of new energy sources such as wind power generation and photovoltaic power generation, in order to ensure the stable access and efficient utilization of new energy power generation, the participation of thermal power units in deep peak regulation has become an inevitable trend. Biomass energy is a renewable zero-carbon fuel. In recent years, with the national strategy, the positioning of the biomass energy industry and its advantages in environmental protection, biomass energy has developed rapidly. Vigorously developing biomass energy utilization technology can effectively reduce carbon dioxide emissions. Biomass and pulverized coal coupling combustion power generation can utilize the advantages of large capacity, high parameters of the original coal-fired unit and the low sulfur and low nitrogen characteristics of the biomass fuel itself. Compared with biomass combustion power generation alone, it has significant advantages in power generation scale, combustion efficiency and operation stability, and can effectively reduce sulfur oxides and nitrogen oxides emissions of the unit.

[0003] In the existing technology, for coal-fired units with a unit capacity greater than or equal to 300MW, the main coupling method is direct combustion coupling, which means that the biomass fuel is processed into a state that can be mixed with coal powder and directly sent into the furnace for mixed combustion. There are also processes that use the products of biomass gasification to mix with coal powder.

[0004] However, the direct coupling method has the problems of poor combustion safety of mixed fuel and poor stable combustion ability at low load. The equipment modification and maintenance costs are high when the products of biomass gasification are mixed with coal powder. Summary of the invention

[0005] The present invention provides a biomass-coupled coal powder fuel system and a control method thereof to solve the problems of poor combustion safety of mixed fuels, low blending ratio, and poor stable combustion ability at low load, thereby reducing equipment modification and maintenance costs.

[0006] According to one aspect of the present invention, a biomass-coupled coal powder fuel system is provided, the biomass-coupled coal powder fuel system comprising: a biomass powder bin, a coal mill, a first conveying pipeline, a second conveying pipeline, a first branch, a second branch and a furnace;

[0007] One end of the first delivery pipeline is connected to the biomass powder bin; the other end of the first delivery pipeline is respectively connected to one end of the first branch and one end of the second branch; the other end of the first branch is connected to the second delivery pipeline; the other end of the second branch is connected to the furnace; the second delivery pipeline is connected between the coal mill and the furnace;

[0008] The biomass powder bin is used to deliver the biomass powder to the second delivery pipeline through the first delivery pipeline and the first branch when the load of the biomass-coupled coal powder fuel system is less than the preset load, and then mix with the coal powder produced by the coal mill and enter the furnace together;

[0009] The biomass powder bin is also used to deliver the biomass powder into the furnace through the first conveying pipeline and the second branch when the load of the biomass-coupled coal powder fuel system is greater than or equal to the preset load; at the same time, the coal mill is used to deliver the produced coal powder into the furnace through the second conveying pipeline.

[0010] Optionally, the biomass-coupled coal powder fuel system further includes: a variable frequency feeding device;

[0011] The variable frequency feeding device is connected between the biomass powder bin and the first conveying pipeline;

[0012] The variable frequency feeding device is used to control the amount of biomass powder entering the furnace for combustion.

[0013] Optionally, the biomass-coated pulverized coal fuel system further includes: a biomass burner and a pulverized coal burner;

[0014] The biomass burner is connected between the second branch and the furnace; the pulverized coal burner is connected between the second conveying pipeline and the furnace;

[0015] The biomass burner is used to be in a closed state when the load of the biomass-coupled coal powder fuel system is less than a preset load; the biomass burner and the coal powder burner are used to be in a working state at the same time when the load of the biomass-coupled coal powder fuel system is greater than or equal to the preset load.

[0016] Optionally, the biomass-coupled coal powder fuel system further includes: a first switch valve and a second switch valve; the first switch valve is arranged at one end of the first branch close to the first delivery pipeline; the second switch valve is arranged at one end of the second branch close to the first delivery pipeline;

[0017] The first switch valve is used to be in an open state when the load of the biomass-coupled coal powder fuel system is less than a preset load, and the second switch valve is used to be in a closed state when the load of the biomass-coupled coal powder fuel system is less than a preset load;

[0018] The first switch valve is also used to be in a closed state when the load of the biomass coupled coal powder fuel system is greater than or equal to a preset load, and the second switch valve is also used to be in an open state when the load of the biomass coupled coal powder fuel system is greater than or equal to a preset load.

[0019] Optionally, the biomass-coated coal powder fuel system further comprises: a pneumatic conveying device; the pneumatic conveying device is respectively connected to the biomass powder bin and the coal mill;

[0020] Pneumatic conveying devices are used to provide conveying media for biomass powder silos and coal mills.

[0021] Optionally, the pneumatic conveying device includes a fan and an air preheater; the fuel system of biomass coupled coal powder also includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline; the fan is located outside the furnace and is connected to one end of the first pipeline and one end of the second pipeline; the air preheater is located in the furnace and is located in the first pipeline; the other end of the first pipeline and the other end of the second pipeline are both connected to one end of the third pipeline; the other end of the third pipeline is respectively connected to one end of the fourth pipeline and one end of the fifth pipeline; the other end of the fourth pipeline is connected to the coal mill; the other end of the fifth pipeline is connected to the biomass powder bin;

[0022] The fan is used to mix the generated air in the third pipeline after passing through the first pipeline and the second pipeline where the air preheater is located, and transport it to the coal mill and the biomass powder bin through the fourth pipeline and the fifth pipeline respectively.

[0023] Optionally, the first switch valve includes an electric valve, a solenoid valve or an isolation door, and / or the second switch valve includes an electric valve, a solenoid valve or an isolation door.

[0024] According to another aspect of the present invention, a control method for a biomass-coupled coal powder fuel system is provided, and the control method for a biomass-coupled coal powder fuel system comprises:

[0025] Determine the load status of the biomass-coupled pulverized coal fuel system;

[0026] When the load of the biomass-coated pulverized coal fuel system is less than the preset load, the biomass powder is controlled to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then enter the furnace together with the pulverized coal produced by the coal mill;

[0027] When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load, the biomass powder is controlled to enter the furnace through the first conveying pipeline and the second branch; the pulverized coal produced by the pulverizer is controlled to enter the furnace through the second conveying pipeline.

[0028] Optionally, when the load of the biomass-coated pulverized coal fuel system is less than a preset load, the biomass powder is controlled to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then mixed with the pulverized coal produced by the coal mill and enter the furnace together, including:

[0029] When the load of the fuel system of biomass coupled with pulverized coal is less than the preset load, the first switch valve is controlled to be in an open state, and the second switch valve is controlled to be in a closed state, and the biomass powder enters the second conveying pipeline through the first conveying pipeline and the first branch, and is mixed with the pulverized coal produced by the coal mill and then enters the pulverized coal burner for combustion, and the generated gas enters the furnace;

[0030] When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, the biomass pulverized coal is controlled to enter the furnace through the first conveying pipeline and the second branch; and the pulverized coal produced by the coal mill is controlled to enter the furnace through the second conveying pipeline, including:

[0031] When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load, the first switch valve is controlled to be in a closed state, and the second switch valve is controlled to be in an open state, and the biomass powder enters the biomass burner through the first conveying pipeline and the second branch for combustion, and the generated gas enters the furnace; at the same time, the pulverized coal produced by the pulverizer enters the pulverized coal burner for combustion through the second conveying pipeline, and the generated gas enters the furnace.

[0032] Optionally, when the load of the biomass-coated pulverized coal fuel system is less than a preset load, the biomass powder is controlled to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then mixed with the pulverized coal produced by the coal mill and enter the furnace together, further comprising:

[0033] When the load of the fuel system of biomass coupled with pulverized coal is less than the preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be less than the preset amount;

[0034] When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, the biomass pulverized coal is controlled to enter the furnace through the first conveying pipeline and the second branch; the pulverized coal produced by the coal mill is controlled to enter the furnace through the second conveying pipeline, and further comprising:

[0035] When the load of the biomass-coated pulverized coal fuel system is greater than or equal to the preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be greater than or equal to the preset amount.

[0036] The technical solution of the embodiment of the present invention is to set up a fuel system of biomass coupled with pulverized coal, and the biomass powder in the biomass powder bin is transported to the furnace for combustion in two ways. When the fuel system is in low-load operation, the biomass powder is sent to the second conveying pipe through the first conveying pipe and the first branch, and is mixed with the pulverized coal produced by the coal mill and then enters the furnace together, and the high volatility and low fixed carbon content of the biomass fuel, as well as the ability to quickly release a large amount of combustible gas during the combustion process, are used to improve the stable combustion ability of the fuel system when it is in low-load operation; when the fuel system is in medium-to-high load operation, the biomass powder is directly sent to the furnace through the first conveying pipe and the second branch, and at the same time, the pulverized coal produced by the coal mill is sent to the furnace through the second conveying pipe, and the biomass powder is sent to the furnace alone for a large proportion of blending and burning, and the characteristics of the alkali metal components in the biomass reacting with the nitrogen oxides to generate nitrates and the low nitrogen characteristics of the biomass itself are used to reduce the nitrogen oxide emission level of the fuel system, and at the same time, the high volatility of the biomass fuel is used to enhance the fuel system's ability to quickly increase the load; a variety of biomass blending methods are used to achieve deep coupling of biomass and pulverized coal, improve the performance of the fuel system, and reduce the cost of transformation.

[0037] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 is a structural schematic diagram of a biomass-coupled coal powder fuel system provided according to an embodiment of the present invention;

[0040] Figure 2 is a flow chart of a control method for a biomass-coupled coal powder fuel system provided according to an embodiment of the present invention;

[0041] Figure 3 The present invention is a flowchart of another method for controlling a biomass-coupled pulverized coal fuel system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] Figure 1 Schematic diagram of a biomass-coated coal-fired fuel system according to an embodiment of the present invention. Figure 1 As shown, the fuel system of biomass coupled with coal powder includes: a biomass powder bin 10, a coal mill 20, a first conveying pipeline 30, a second conveying pipeline 40, a first branch 301, a second branch 302 and a furnace 50; one end of the first conveying pipeline 30 is connected to the biomass powder bin 10; the other end of the first conveying pipeline 30 is respectively connected to one end of the first branch 301 and one end of the second branch 302; the other end of the first branch 301 is connected to the second conveying pipeline 40; the other end of the second branch 302 is connected to the furnace 50; the second conveying pipeline 40 is connected between the coal mill 20 and the furnace The biomass powder bin 10 is used to deliver the biomass powder into the second delivery pipe 40 through the first delivery pipe 30 and the first branch 301 when the load of the biomass-coupled pulverized coal fuel system is less than the preset load, and the biomass powder is mixed with the pulverized coal produced by the pulverizer 20 and then enters the furnace 50 together; the biomass powder bin 10 is also used to deliver the biomass powder into the furnace 50 through the first delivery pipe 30 and the second branch 302 when the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load; at the same time, the pulverizer 20 is used to deliver the produced pulverized coal into the furnace 50 through the second delivery pipe 40.

[0045] In the embodiment of the present invention, the biomass powder bin 10 is a container for storing biomass powder, which plays a role in biomass storage and supply in the entire fuel system. The coal mill 20 is mainly used to grind coal raw materials into coal powder to provide coal powder fuel for combustion. The first delivery pipeline 30 is the initial transmission channel for biomass powder starting from the biomass powder bin 10, and is connected to two different branches, the first branch 301 and the second branch 302, to provide a basis for different subsequent delivery paths of biomass powder. The first branch 301 is the transmission channel for biomass powder when the fuel system load is low. The biomass powder is transmitted to the second delivery pipeline 40 through the first branch 301 to mix with coal powder. The second branch 302 is the transmission channel for biomass powder when the fuel system load is high. The biomass powder is directly transmitted to the furnace 50 through the second branch 302, so that the biomass powder enters the furnace 50 alone without mixing with coal powder. The furnace 50 is the main place for combustion, which is used to convert the generated heat energy into electrical energy or provide energy for other industrial processes.

[0046] The preset load is the preset operating load of the biomass-coupled coal powder fuel system. Exemplarily, the preset load is 30% of the rated evaporation capacity. When the load of the biomass-coupled coal powder fuel system is less than the preset load, the operating load of the biomass-coupled coal powder fuel system may be between 20% of the rated evaporation capacity and 30% of the rated evaporation capacity. When the load of the biomass-coupled coal powder fuel system is greater than or equal to the preset load, the operating load of the biomass-coupled coal powder fuel system may be between 30% of the rated evaporation capacity and 100% of the rated evaporation capacity. The embodiment of the present invention can realize the use of different methods to add biomass fuel as needed according to the load of the fuel system. When the fuel system is running at a low load, the biomass powder is sent into the second delivery pipeline 40 through the first delivery pipeline 30 and the first branch 301, and is mixed with the coal powder produced by the pulverizer 20 and then enters the furnace 50 together. By mixing the highly volatile biomass powder with the coal powder, the stable combustion ability of the fuel system can be enhanced. When the fuel system is running at medium and high loads, the temperature of the furnace 50 is high, and the nitrogen oxide emissions increase. The biomass powder is directly delivered to the furnace 50 through the first delivery pipeline 30 and the second branch 302. At the same time, the coal powder produced by the pulverizer 20 is also directly delivered to the furnace 50 through the second delivery pipeline 40. By burning biomass powder in the upper layer of the furnace 50, the nitrogen oxide emissions can be effectively reduced, and the operating cost of the denitrification system can be reduced. By burning a large proportion of biomass, the fuel system's ability to increase load is enhanced. By adjusting the addition of biomass powder on demand, efficient energy utilization in the biomass disposal process is achieved.

[0047] The technical solution of the embodiment of the present invention provides a fuel system that couples biomass with pulverized coal. The biomass powder in the biomass powder silo is transported to the furnace for combustion in two paths. When the fuel system is operating at low load, the biomass powder is sent into the second conveying pipeline through the first conveying pipeline and the first branch, and after being mixed with the pulverized coal produced by the coal mill, they jointly enter the furnace. By utilizing the high volatility and low fixed carbon content of biomass fuel, and the ability to rapidly release a large amount of combustible gas during the combustion process, the stable combustion capacity of the fuel system during low-load operation is enhanced. When the fuel system is operating at medium to high load, the biomass powder is directly sent into the furnace through the first conveying pipeline and the second branch. At the same time, the pulverized coal produced by the coal mill is sent into the furnace through the second conveying pipeline. The biomass powder is sent into the furnace alone for a relatively large proportion of co-firing. By utilizing the characteristic that the alkali metal components in biomass react with nitrogen oxides to form nitrates and the low-nitrogen characteristic of biomass itself, the nitrogen oxide emission level of the fuel system is reduced. At the same time, the high volatility of biomass fuel is used to enhance the ability of the fuel system to rapidly increase the load. Multiple biomass co-firing methods are adopted to achieve deep coupling of biomass and pulverized coal, improve the performance of the fuel system, and reduce the transformation cost.

[0048] Based on the above technical solution of the embodiment of the invention, referring to Figure 1 , optionally, the fuel system that couples biomass with pulverized coal further includes: a variable-frequency feeding device 60; the variable-frequency feeding device 60 is connected between the biomass powder silo 10 and the first conveying pipeline 30; the variable-frequency feeding device 60 is used to control the co-firing amount of the biomass powder entering the furnace 50.

[0049] In an embodiment of the present invention, the variable frequency feeding device 60 includes but is not limited to a variable frequency feeder. A variable frequency feeder is a device used for precise feeding and flow control of materials. The speed of the motor is changed by variable frequency speed regulation technology, thereby adjusting the feeding speed of the feeder. The motor drives the conveying components of the feeder, such as a belt or a screw. When the motor speed changes, the operating speed of the conveying components also changes accordingly, thereby achieving precise control of the material flow rate. In an embodiment of the present invention, the variable frequency feeding device 60 is connected between the biomass powder bin 10 and the first conveying pipeline 30, and is used to control the amount of biomass powder entering the furnace 50 for combustion. Exemplarily, when the fuel system is running at a low load, the biomass powder is fed into the second delivery pipe 40 through the first delivery pipe 30 and the first branch 301, mixed with the coal powder produced by the pulverizer 20 and then enters the furnace 50 together. By calculating the mass ratio of coal powder to biomass powder, the variable frequency feeding device 60 controls the biomass powder blending amount to be less than 20% of the total fuel amount, so as to prevent the flame at the outlet of the combustion device from approaching the combustion device due to excessive biomass blending, and prevent incomplete combustion from causing high residual carbon content. At the same time, due to the high volatility and low fixed carbon content of biomass powder, it can quickly release a large amount of combustible gas during the combustion process, thereby enhancing the stable combustion ability of the fuel system. When the fuel system is running at medium and high loads, the temperature of the furnace 50 is high, and the emission of nitrogen oxides increases. The biomass powder is directly delivered to the furnace 50 through the first delivery pipeline 30 and the second branch 302. At the same time, the coal powder produced by the coal mill 20 is also directly delivered to the furnace 50 through the second delivery pipeline 40. By burning biomass powder in the upper layer of the furnace 50, the emission of nitrogen oxides can be effectively reduced, and the operating cost of the denitrification system can be reduced. By calculating the mass ratio of coal powder to biomass powder, the variable frequency feeding device 60 controls the amount of biomass powder to be greater than or equal to 20% of the total amount of fuel. By burning a large proportion of biomass, the load of the fuel system can be quickly increased.

[0050] Based on the technical solution of the above invention embodiment, Figure 1 Optionally, the biomass-coupled pulverized coal fuel system further includes: a biomass burner 70 and a pulverized coal burner 80; the biomass burner 70 is connected between the second branch 302 and the furnace 50; the pulverized coal burner 80 is connected between the second delivery pipeline 40 and the furnace 50; the biomass burner 70 is used to be in a closed state when the load of the biomass-coupled pulverized coal fuel system is less than a preset load; the biomass burner 70 and the pulverized coal burner 80 are used to be in a working state at the same time when the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load.

[0051] In the embodiment of the present invention, the biomass burner 70 is a device that converts biomass fuel into thermal energy. The pulverized coal burner 80 is a device that efficiently burns pulverized coal to release thermal energy. When the fuel system is running at a low load, the biomass burner 70 is in a closed state, and only the pulverized coal burner 80 is in a working state. Since the anti-interference ability of the pulverized coal burner 80 is greatly weakened, the stable combustion ability of the fuel system can be enhanced by mixing and burning highly volatile biomass powder with pulverized coal. When the fuel system is running at medium and high loads, due to the high temperature of the furnace 50, the nitrogen oxide emissions increase. By mixing and burning biomass powder in the upper layer of the furnace 50, the biomass burner 70 and the pulverized coal burner 80 are both in a working state, which can effectively reduce the nitrogen oxide emissions, reduce the operating cost of the denitrification system, and increase the boiler's load capacity by mixing and burning a large proportion of biomass. The energy efficient utilization in the biomass disposal process is achieved by adjusting the biomass fuel on demand.

[0052] Based on the technical solution of the above invention embodiment, Figure 1 Optionally, the biomass-coupled pulverized coal fuel system further includes: a first switch valve 101 and a second switch valve 102; the first switch valve 101 is arranged at one end of the first branch 301 close to the first delivery pipeline 30; the second switch valve 102 is arranged at one end of the second branch 302 close to the first delivery pipeline 30; the first switch valve 101 is used to be in an open state when the load of the biomass-coupled pulverized coal fuel system is less than a preset load, and the second switch valve 102 is used to be in a closed state when the load of the biomass-coupled pulverized coal fuel system is less than a preset load; the first switch valve 101 is also used to be in a closed state when the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load, and the second switch valve 102 is also used to be in an open state when the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load.

[0053] In the embodiment of the present invention, a first switch valve 101 and a second switch valve 102 are provided to adjust the biomass blending mode. The first switch valve 101 is provided at one end of the first branch 301 close to the first delivery pipeline 30 to prevent the blockage of biomass powder during the switching process of the first switch valve 101. When the load of the fuel system is less than the preset load, the first switch valve 101 is opened, the second switch valve 102 is closed, and the biomass powder is sent to the second delivery pipeline 40 through the first delivery pipeline 30 and the first branch 301, and mixed with the coal powder produced by the coal mill 20 and then enter the furnace 50 together. The second switch valve 102 is provided at one end of the second branch 302 close to the first delivery pipeline 30 to prevent the blockage of biomass powder during the switching process of the second switch valve 102. When the load of the fuel system is greater than or equal to the preset load, the first switch valve 101 is closed, the second switch valve 102 is opened, and the biomass powder is directly sent to the furnace 50 through the first delivery pipeline 30 and the second branch 302 without mixing with the coal powder.

[0054] Based on the technical solution of the above invention embodiment, Figure 1 Optionally, the biomass-coupled coal powder fuel system also includes: a pneumatic conveying device 90; the pneumatic conveying device 90 is connected to the biomass powder bin 10 and the coal mill 20 respectively; the pneumatic conveying device 90 is used to provide a conveying medium for the biomass powder bin 10 and the coal mill 20.

[0055] In the embodiment of the present invention, the transport medium may be hot air. For example, the biomass fuel is stored in the biomass powder bin 10, and the biomass fuel is transported using the hot air provided by the pneumatic transport device 90 as the transport medium to transport the biomass fuel to the corresponding pipeline.

[0056] Based on the technical solution of the above invention embodiment, Figure 1 Optionally, the pneumatic conveying device 90 includes a fan 901 and an air preheater 902; the fuel system of biomass coupled with pulverized coal also includes a first pipeline 903, a second pipeline 904, a third pipeline 905, a fourth pipeline 906 and a fifth pipeline 907; the fan 901 is located outside the furnace 50 and is connected to one end of the first pipeline 903 and one end of the second pipeline 904; the air preheater 902 is located inside the furnace 50 and is located in the first pipeline 903; the other end of the first pipeline 903 and the other end of the second pipeline 904 are both connected to the third pipeline 906. 05; the other end of the third pipeline 905 is respectively connected to one end of the fourth pipeline 906 and one end of the fifth pipeline 907; the other end of the fourth pipeline 906 is connected to the coal mill 20; the other end of the fifth pipeline 907 is connected to the biomass powder bin 10; the fan 901 is used to mix the generated wind in the third pipeline 905 after passing through the first pipeline 903 and the second pipeline 904 where the air preheater 902 is located, and transport it to the coal mill 20 and the biomass powder bin 10 through the fourth pipeline 906 and the fifth pipeline 907 respectively.

[0057] In an embodiment of the present invention, the fuel system of biomass coupled with coal powder also includes a third switch valve 103 and a fourth switch valve 104. The third switch valve 103 is arranged in the fourth pipeline 906, and is used to regulate the amount of air entering the coal mill 20. The fourth switch valve 104 is arranged in the fifth pipeline 907, and is used to regulate the amount of air entering the biomass powder bin 10. The fan 901 is a device that relies on input mechanical energy to increase the gas pressure and discharge the gas. The air preheater 902 can heat and output the gas generated by the fan 901. The hot air provided by the pneumatic conveying device 90 can be a cold and hot primary mixed air at the inlet and outlet of the air preheater 902. In other optional embodiments of the present invention, an air heater can also be provided to heat the biomass conveying air.

[0058] Based on the technical solution of the above invention embodiment, Figure 1Optionally, the first switch valve 101 includes an electric valve, a solenoid valve or an isolation door, and / or the second switch valve 102 includes an electric valve, a solenoid valve or an isolation door.

[0059] In the embodiment of the present invention, the first switch valve 101 and the second switch valve 102 include but are not limited to being set as a manual isolation door, an electric isolation door, an electric valve or a solenoid valve to achieve control of different transmission paths of the biomass fuel.

[0060] Figure 2 This is a flow chart of a control method for a biomass-coupled coal powder fuel system according to an embodiment of the present invention. This embodiment can be applied to the control of a biomass-coupled coal powder fuel system. The control method for the biomass-coupled coal powder fuel system can be executed by a control device for the biomass-coupled coal powder fuel system. The control device for the biomass-coupled coal powder fuel system can be implemented in the form of hardware and / or software. Figure 2 As shown, the control method of the biomass-coupled coal powder fuel system includes:

[0061] S110. Determine a load state of a biomass-coupled coal powder fuel system.

[0062] Specifically, the load state of the biomass-coupled pulverized coal fuel system is determined according to external needs. When the heating demand is low, the biomass-coupled pulverized coal fuel system is in a low-load state to avoid excessive energy consumption. When the heating demand is high, more hot water or steam supply is required, and the biomass-coupled pulverized coal fuel system is in a high-load state to meet production needs.

[0063] S120. When the load of the biomass-coupled pulverized coal fuel system is less than a preset load, the biomass powder is controlled to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then enter the furnace together with the pulverized coal produced by the pulverizer after being mixed.

[0064] When the biomass-coupled pulverized coal fuel system operates at a low load, exemplarily, the operating load of the biomass-coupled pulverized coal fuel system is between 20% and 30% of the rated evaporation capacity. The biomass powder is sent to the second delivery pipeline through the first delivery pipeline and the first branch, and is mixed with the pulverized coal produced by the pulverizer and then enters the furnace together. By mixing the highly volatile biomass powder with the pulverized coal, the stable combustion ability of the fuel system can be enhanced.

[0065] S130. When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, the biomass pulverized coal is controlled to enter the furnace through the first conveying pipeline and the second branch; and the pulverized coal produced by the coal mill is controlled to enter the furnace through the second conveying pipeline.

[0066] Specifically, when the fuel system is running at medium and high loads, for example, the operating load of the biomass-coupling coal powder fuel system is between 30% and 100% of the rated evaporation capacity. Due to the high furnace temperature, the nitrogen oxide emissions increase. The biomass powder is directly delivered to the furnace through the first delivery pipeline and the second branch. At the same time, the coal powder produced by the pulverizer is also directly delivered to the furnace through the second delivery pipeline. By burning biomass powder in the upper layer of the furnace, the nitrogen oxide emissions can be effectively reduced, and the operating cost of the denitrification system can be reduced. By adjusting the biomass powder on demand, efficient energy utilization in the biomass disposal process is achieved.

[0067] The technical solution of the embodiment of the present invention is to set a control method for a fuel system of biomass coupled with pulverized coal. By determining the load state of the fuel system of biomass coupled with pulverized coal, when the fuel system is in low-load operation, the biomass powder is controlled to be sent into the second conveying pipeline through the first conveying pipeline and the first branch, and mixed with the pulverized coal produced by the pulverizer and then enter the furnace together, and the high volatility and low fixed carbon content of the biomass fuel, as well as the ability to quickly release a large amount of combustible gas during the combustion process, are used to improve the stable combustion ability of the fuel system when it is in low-load operation; when the fuel system is in medium-to-high load operation, the biomass powder is controlled to be directly sent into the furnace through the first conveying pipeline and the second branch, and at the same time, the pulverized coal produced by the pulverizer is sent into the furnace through the second conveying pipeline, and the biomass powder is sent into the furnace alone for a large proportion of blending and burning, and the characteristics of the alkali metal components in the biomass reacting with nitrogen oxides to generate nitrates and the low nitrogen characteristics of the biomass itself are used to reduce the nitrogen oxide emission level of the fuel system, and at the same time, the high volatility of the biomass fuel is used to enhance the fuel system's ability to quickly increase the load; a variety of biomass blending methods are used to achieve deep coupling of biomass and pulverized coal, improve the performance of the fuel system, and reduce the cost of transformation.

[0068] Figure 3 1 is a flow chart of another control method of a biomass-coated coal-fired fuel system according to an embodiment of the present invention. This embodiment is a detailed description of the technical features of the above embodiment. Figure 3 As shown, the control method of the biomass-coupled coal powder fuel system includes:

[0069] S210. Determine a load state of a biomass-coupled pulverized coal fuel system.

[0070] S220. When the load of the fuel system of biomass coupled with pulverized coal is less than the preset load, the first switch valve is controlled to be in an open state, and the second switch valve is controlled to be in a closed state. The biomass powder enters the second conveying pipeline through the first conveying pipeline and the first branch, and after being mixed with the pulverized coal produced by the pulverizer, they enter the pulverized coal burner for combustion, and the generated gas enters the furnace.

[0071] In an optional embodiment of the present invention, when the load of the biomass-coated pulverized coal fuel system is less than a preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be less than a preset amount.

[0072] In an embodiment of the present invention, the preset blending amount is the preset amount of biomass powder entering the burner. Exemplarily, the preset blending amount is 20% of the total fuel. When the fuel system is running at low load, the biomass powder is sent into the second delivery pipeline through the first delivery pipeline and the first branch, and is mixed with the coal powder produced by the coal mill and then enters the pulverized coal burner together. By calculating the mass ratio of coal powder to biomass powder, the variable frequency feeding device controls the biomass powder blending amount to be less than 20% of the total fuel amount, so as to prevent the excessive biomass blending amount from causing the flame at the outlet of the pulverized coal burner to approach the pulverized coal burner, and the incomplete combustion from causing the residual carbon content to be high. At the same time, due to the high volatility and low fixed carbon content of biomass powder, it can quickly release a large amount of combustible gas during the combustion process, thereby enhancing the stable combustion ability of the fuel system.

[0073] S230. When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to the preset load, the first switch valve is controlled to be in a closed state, and the second switch valve is controlled to be in an open state. The biomass powder enters the biomass burner through the first conveying pipeline and the second branch for combustion, and the generated gas enters the furnace; at the same time, the pulverized coal produced by the pulverizer enters the pulverized coal burner through the second conveying pipeline for combustion, and the generated gas enters the furnace.

[0074] In an optional embodiment of the present invention, when the load of the biomass-coupled coal powder fuel system is greater than or equal to a preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be greater than or equal to a preset amount.

[0075] In the embodiment of the present invention, when the fuel system is running at medium and high loads, the nitrogen oxide emissions increase due to the high furnace temperature. The biomass powder is directly sent to the biomass burner through the first delivery pipeline and the second branch. At the same time, the coal powder produced by the coal mill is sent to the coal powder burner through the second delivery pipeline. By burning biomass powder in the upper layer of the furnace, the nitrogen oxide emissions can be effectively reduced, and the operating cost of the denitrification system can be reduced. By calculating the mass ratio of coal powder to biomass powder, the variable frequency feeding device controls the amount of biomass powder to be greater than or equal to 20% of the total fuel amount. By burning a large proportion of biomass, the fuel system load can be quickly increased.

[0076] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0077] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A biomass-coated coal powder fuel system, characterized in that: include: A biomass powder silo, a coal mill, a first conveying pipeline, a second conveying pipeline, a first branch, a second branch, and a furnace; One end of the first delivery pipeline is connected to the biomass powder bin; the other end of the first delivery pipeline is respectively connected to one end of the first branch and one end of the second branch; the other end of the first branch is connected to the second delivery pipeline; the other end of the second branch is connected to the furnace; the second delivery pipeline is connected between the coal mill and the furnace; The biomass powder bin is used to deliver the biomass powder into the second delivery pipeline through the first delivery pipeline and the first branch when the load of the biomass-coated pulverized coal fuel system is less than a preset load, and the biomass powder is mixed with the pulverized coal produced by the coal mill and then enters the furnace together; The biomass powder bin is also used to deliver the biomass powder into the furnace through the first conveying pipeline and the second branch when the load of the biomass-coupled coal powder fuel system is greater than or equal to a preset load; at the same time, the pulverizer is used to deliver the produced coal powder into the furnace through the second conveying pipeline.

2. The biomass-coupled coal powder fuel system according to claim 1, characterized in that: Also includes: Frequency conversion feeding device; The variable frequency feeding device is connected between the biomass powder bin and the first conveying pipeline; The variable frequency feeding device is used to control the amount of biomass powder entering the furnace for combustion.

3. The biomass-coated coal powder fuel system according to claim 2, characterized in that: Also includes: Biomass burners and pulverized coal burners; The biomass burner is connected between the second branch and the furnace; The pulverized coal burner is connected between the second delivery pipeline and the furnace; The biomass burner is used to be in a closed state when the load of the biomass-coupled coal powder fuel system is less than a preset load; the biomass burner and the coal powder burner are used to be in a working state at the same time when the load of the biomass-coupled coal powder fuel system is greater than or equal to the preset load.

4. The biomass-coupled coal powder fuel system according to claim 1, characterized in that: Also includes: A first switch valve and a second switch valve; the first switch valve is arranged at one end of the first branch close to the first delivery pipeline; the second switch valve is arranged at one end of the second branch close to the first delivery pipeline; The first switch valve is used to be in an open state when the load of the biomass-coupled coal powder fuel system is less than a preset load, and the second switch valve is used to be in a closed state when the load of the biomass-coupled coal powder fuel system is less than a preset load; The first switch valve is also used to be in a closed state when the load of the biomass-coupled coal powder fuel system is greater than or equal to a preset load, and the second switch valve is also used to be in an open state when the load of the biomass-coupled coal powder fuel system is greater than or equal to a preset load.

5. The biomass-coupled coal powder fuel system according to claim 1, characterized in that: Also includes: Pneumatic conveying devices; The pneumatic conveying device is connected to the biomass powder bin and the coal mill respectively; The pneumatic conveying device is used to provide a conveying medium for the biomass powder bin and the coal mill.

6. The biomass-coupled coal powder fuel system according to claim 5, characterized in that: The pneumatic conveying device includes a fan and an air preheater; the biomass-coupled coal powder fuel system also includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline; The fan is located outside the furnace and connected to one end of the first pipeline and one end of the second pipeline; the air preheater is located inside the furnace and located in the first pipeline; The other end of the first pipeline and the other end of the second pipeline are both connected to one end of the third pipeline; the other end of the third pipeline is respectively connected to one end of the fourth pipeline and one end of the fifth pipeline; the other end of the fourth pipeline is connected to the coal mill; the other end of the fifth pipeline is connected to the biomass powder bin; The fan is used to mix the generated air in the third pipeline after passing through the first pipeline and the second pipeline where the air preheater is located, and transport the generated air to the coal mill and the biomass powder bin through the fourth pipeline and the fifth pipeline respectively.

7. The biomass-coupled coal powder fuel system according to claim 4, characterized in that: The first switch valve includes an electric valve, a solenoid valve or an isolation door, and / or the second switch valve includes an electric valve, a solenoid valve or an isolation door.

8. A control method for a biomass-coated coal powder fuel system, characterized in that: A biomass-coupled coal powder fuel system applied to any one of claims 1 to 7; a control method of the biomass-coupled coal powder fuel system comprises: Determining a load state of the biomass-coupled pulverized coal fuel system; When the load of the biomass-coated pulverized coal fuel system is less than a preset load, the biomass powder is controlled to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then enter the furnace together with the pulverized coal produced by the coal mill after being mixed; When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, the biomass powder is controlled to enter the furnace through the first conveying pipeline and the second branch; the pulverized coal produced by the pulverizer is controlled to enter the furnace through the second conveying pipeline.

9. The control method of the biomass-coupled coal powder fuel system according to claim 8, characterized in that: When the load of the biomass-coated pulverized coal fuel system is less than a preset load, controlling the biomass powder to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then mixing with the pulverized coal produced by the coal mill and entering the furnace together, comprises: When the load of the biomass-coated pulverized coal fuel system is less than a preset load, the first switch valve is controlled to be in an open state, and the second switch valve is controlled to be in a closed state, and the biomass powder enters the second delivery pipeline through the first delivery pipeline and the first branch, and is mixed with the pulverized coal produced by the coal mill and then enters the pulverized coal burner for combustion, and the generated gas enters the furnace; When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, controlling the biomass pulverized coal to enter the furnace through the first conveying pipeline and the second branch; and controlling the pulverized coal produced by the coal mill to enter the furnace through the second conveying pipeline, comprising: When the load of the biomass-coupled pulverized coal fuel system is greater than or equal to a preset load, the first switch valve is controlled to be in a closed state, and the second switch valve is controlled to be in an open state, and the biomass powder enters the biomass burner through the first conveying pipeline and the second branch for combustion, and the generated gas enters the furnace; at the same time, the pulverized coal produced by the pulverizer enters the pulverized coal burner for combustion through the second conveying pipeline, and the generated gas enters the furnace.

10. The control method of the biomass-coupled coal powder fuel system according to claim 8, characterized in that: When the load of the biomass-coated pulverized coal fuel system is less than a preset load, controlling the biomass pulverized coal to enter the second conveying pipeline through the first conveying pipeline and the first branch, and then mixing with the pulverized coal produced by the coal mill and entering the furnace together, further comprising: When the load of the biomass-coated pulverized coal fuel system is less than a preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be less than a preset amount; When the load of the biomass-coated pulverized coal fuel system is greater than or equal to a preset load, controlling the biomass pulverized coal to enter the furnace through the first conveying pipeline and the second branch; controlling the pulverized coal produced by the coal mill to enter the furnace through the second conveying pipeline, further comprising: When the load of the biomass-coated pulverized coal fuel system is greater than or equal to a preset load, the variable frequency feeding device is adjusted to control the amount of biomass powder entering the furnace to be greater than or equal to the preset amount.

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