Double-source multi-combustion system

Abstract

The invention discloses a double-source multi-combustion system, which comprises a boiler, a combustion chamber, a combustion chamber, a combustion chamber, a combustion chamber and at least two air and powder combustors, the main combustion coal mills are communicated with one or more wind powder combustors; the plurality of powder storage coal mills are communicated with other air powder combustors in the boiler; the gas drying system is respectively communicated with the main combustion coal mill and the powder storage coal mill, and is used for drying and conveying coal ground in the main combustion coal mill and the powder storage coal mill to form primary air powder; the fine powder separators are used for separating primary air powder to form pulverized coal and exhaust gas; the exhaust gas fans are used for collecting exhaust gas, and outlets of the exhaust gas fans are respectively communicated with the exhaust gas burner and the powder storage coal mill; the pulverized coal bins are used for collecting pulverized coal generated in the fine powder separator; and the thermal medium powder feeding system is used for conveying the pulverized coal in the pulverized coal bunker to the pulverized coal bunker burner, and the gas drying system is further communicated with the thermal medium powder feeding system to preheat the pulverized coal conveyed into the pulverized coal bunker burner.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and particularly to a dual-source multi-fuel system. Background Art

[0002] The change in coal price is crucial for the profit of coal-fired power units, and the prices of different coal types also vary greatly. Considering the profitability of power plants, power plants often mix a large amount of economically viable coal types such as high-moisture lignite and low-volatile lean coal to reduce costs. This has led to an increasingly broad range of coal types used in power plant coal combustion, often exceeding the applicable range of existing boiler coal pulverizing systems.

[0003] In addition, in the construction of a new power system with new energy as the main body, the positioning of new energy as the main power source has been clarified, and the role of coal power has undergone a fundamental transformation, from the main power source to a basic guarantee and system regulation power source that provides reliable capacity, peak shaving, frequency modulation and other auxiliary services. At this stage, the policy environment is based on the "dual carbon" goal and energy security, emphasizing the deep peak shaving, rapid load change and wide-load high efficiency of coal-fired power units. With the continuous improvement of the peak shaving depth and rapid load change rate requirements of the power grid for coal-fired power units, the boiler coal pulverizing systems of traditional coal-fired power units are difficult to meet these requirements (the working principle of the boiler coal pulverizing system is that raw coal is fed into the coal mill of the coal pulverizing system, ground and dried into pulverized coal, and then fed into the burner of the boiler for combustion to provide heat input to the boiler).

[0004] The boiler coal pulverizing systems of existing power plants mostly adopt medium-speed coal mill direct-fired coal pulverizing systems. For example, Figure 1 As shown, the hot primary air from the boiler is mixed with the cold primary air, and the formed mixed medium is respectively fed into coal mill A and coal mill B to dry and convey the coal being ground in coal mill A and coal mill B. After drying, primary air powder is formed; the primary air powder formed in coal mills A and B is discharged from the upper part of the coal mill and conveyed through pipelines to the primary air powder burners A and B of the boiler for combustion to provide heat to the boiler; usually, each boiler is provided with 2 or more coal mills and related inlet and outlet pipelines, and each coal mill can operate independently.

[0005] However, the current boiler coal pulverizing system has the following disadvantages: (1) Narrow coal type adaptability: It is usually only applicable to bituminous coal with relatively high volatile content and low moisture, not suitable for lignite with high moisture. Limited by the hot air temperature at the inlet of the coal mill (usually below 300°C), the drying capacity of the original coal pulverizing system is limited, and it is unable to completely dry lignite with high moisture, resulting in too low primary air powder temperature at the outlet of the coal mill, unable to meet the requirements of stable combustion of the boiler, restricting the range of available coal types for the power plant and affecting the economic benefits of the power plant; (2) Not conducive to deep peak shaving operation of coal-fired power units: When the unit performs deep peak shaving, the hot air temperature at the inlet of the coal mill is very low (for example, the hot air temperature at the inlet of the coal mill is only 230°C when the unit load is 20%). The drying capacity of the coal mill is severely restricted, resulting in the primary air powder temperature at the outlet of the coal mill being much lower than the conventional 70°C, affecting the stable combustion of the boiler and the safe operation of the boiler under deep peak shaving; (3) Not conducive to rapid load change of coal-fired power units: To improve the operation flexibility of the unit under complex coal quality conditions, the problem of fuel supply must be solved first. When the unit increases the load, the coal pulverizing system should be able to quickly increase sufficient fuel (pulverized coal). However, the existing coal pulverizing system has the disadvantage of lag in fuel increase. It usually takes 5 - 10 minutes from the coal-fired power unit receiving the fuel increase instruction to the outlet of the boiler primary air powder burner generating primary air powder that meets the combustion concentration requirements, seriously affecting the rapid load change rate of the coal-fired power unit; (4) The coal pulverizing system has a risk of deflagration, affecting safety: Since the existing boiler coal pulverizing system is only applicable to bituminous coal, and bituminous coal has a relatively high volatile content, it is easy to cause deflagration of the coal pulverizing system. Especially under deep peak shaving of the unit, the power plant is more inclined to burn coal types with high volatile content to ensure the stable combustion of the boiler, which further exacerbates the risk of deflagration. Summary of the Invention

[0006] The purpose of the present invention is to design a dual-source multi-fuel system to solve the above problems for the above problems existing in the existing boiler coal pulverizing system.

[0007] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0008] The present invention designs a dual-source multi-fuel system, and this dual-source multi-fuel system includes the following structural settings:

[0009] A boiler, which is provided with at least one flue gas burner, at least one bin burner, and at least two primary air powder burners;

[0010] Several main combustion coal mills, which are used for coal grinding to produce pulverized coal, and the main combustion coal mills are connected to one or several primary air powder burners in the boiler;

[0011] Several storage pulverized coal mills, which are used for coal grinding to produce pulverized coal, and several storage pulverized coal mills are respectively connected to the remaining primary air powder burners in the boiler;

[0012] A gas drying system is connected to the main combustion coal mill and the powder storage coal mill respectively. The gas drying system is used to dry the coal ground in the main combustion coal mill and the powder storage coal mill, and to convey the pulverized coal generated after grinding to downstream equipment and the pulverized coal-air burner. During the conveying process, primary pulverized coal-air is formed.

[0013] A number of fine powder separators are arranged downstream of the powder storage coal mill and are connected to it, and are used to separate the primary pulverized coal-air conveyed from the powder storage coal mill to form pulverized coal and exhausted gas.

[0014] A number of exhausted gas fans are arranged downstream of the fine powder separator and are connected to it to collect the exhausted gas generated in the fine powder separator. The outlets of the exhausted gas fans are respectively connected to the exhausted gas burner in the boiler and the powder storage coal mill.

[0015] A number of pulverized coal bins are arranged downstream of the fine powder separator and are connected to it to collect the pulverized coal generated in the fine powder separator.

[0016] A hot medium powder feeding system is arranged downstream of the pulverized coal bin and is connected to it, and is used to convey the pulverized coal in the pulverized coal bin to the pulverized coal burner in the bin. The gas drying system is also connected to the hot medium powder feeding system and is used to preheat the pulverized coal conveyed to the pulverized coal burner in the bin.

[0017] Specifically, the connection from the powder storage coal mill to the fine powder separator can be led out from the equipment body of the powder storage coal mill or from the pipeline at the outlet of the total powder storage coal mill.

[0018] Further, a dual-source multi-fuel combustion system: the number of the pulverized coal-air burners is the same as or different from the sum of the numbers of the main combustion coal mill and the powder storage coal mill.

[0019] Further, a dual-source multi-fuel combustion system: the number of the fine powder separators is the same as or different from the number of the powder storage coal mills.

[0020] Further, a dual-source multi-fuel combustion system: the gas drying system includes: a first drying gas unit and a second drying gas unit; the gas drying system may or may not include a third drying gas unit;

[0021] Among them, the first drying gas unit is respectively connected to a number of main combustion coal mills, a number of powder storage coal mills and the hot medium powder feeding system;

[0022] The second drying gas unit is respectively connected to a number of main combustion coal mills, a number of powder storage coal mills and the hot medium powder feeding system;

[0023] The third drying gas unit is respectively and communicatively arranged with a plurality of main combustion coal mills, a plurality of coal powder storage mills, and a hot medium coal powder feeding system.

[0024] Furthermore, a dual-source multi-fuel combustion system: The first drying gas unit is divided into five paths. One path is directly communicatively arranged with a plurality of coal powder storage mills respectively. One path is arranged close to the upstream of the pulverized coal burner communicatively connected with the coal powder storage mill. One path is communicatively arranged with the hot medium coal powder feeding system. One path is communicatively arranged with a plurality of main combustion coal mills. The remaining one path is arranged close to the upstream of the pulverized coal burner communicatively connected with the main combustion coal mill. The second drying gas unit is also divided into five paths. One path is directly communicatively arranged with a plurality of coal powder storage mills respectively. One path is arranged close to the upstream of the pulverized coal burner communicatively connected with the coal powder storage mill. One path is communicatively arranged with the hot medium coal powder feeding system. One path is communicatively arranged with a plurality of main combustion coal mills. The remaining one path is arranged close to the upstream of the pulverized coal burner communicatively connected with the main combustion coal mill.

[0025] Specifically, the third drying gas unit is divided into three paths. One path is directly communicatively arranged with a plurality of coal powder storage mills respectively. Another path is communicatively arranged with the hot medium coal powder feeding system. The remaining one path is communicatively arranged with a plurality of main combustion coal mills.

[0026] Furthermore, a dual-source multi-fuel combustion system: The first drying gas in the first drying gas unit comes from this boiler and / or an adjacent boiler. The first drying gas is the hot primary air of the boiler. The second drying gas in the second drying gas unit comes from this boiler and / or an adjacent boiler. The second drying gas is the cold primary air of the boiler. The third drying gas in the third drying gas unit comes from this boiler and / or an adjacent boiler. The third drying gas is the flue gas inside or at the outlet of the boiler.

[0027] Furthermore, a dual-source multi-fuel combustion system: The gas drying system is set to include or not include the third drying gas unit according to the volatile matter of the coal ground in the main combustion coal mills and the coal powder storage mills. For coal with low volatile matter, the third drying gas unit is not set. Otherwise, it is set.

[0028] Further, a dual-source multi-fuel combustion system: The hot medium coal powder feeding system includes: a plurality of impeller coal feeders and a plurality of coal powder mixers. The impeller coal feeders are arranged downstream of the coal powder bin and communicatively connected therewith. The coal powder mixers are arranged downstream of the impeller coal feeders and communicatively connected therewith. The impeller coal feeders are used to convey the coal powder in the coal powder bin to the coal powder mixers. The outlet of the coal powder mixer is communicatively connected with the pulverized coal burner.

[0029] Specifically, the number of impeller coal feeders is equal to the number of coal powder mixers, and the number of pulverized coal burners is the same as or in a multiple relationship of natural numbers with the number of coal powder mixers.

[0030] Furthermore, a dual-source multi-fuel system: the gas drying system is communicatively connected to the inlet of the pulverized coal mixer.

[0031] Further, a dual-source multi-fuel system: the main coal mill and the coal powder storage mill are respectively selected from medium-speed coal mills or double-in and double-out steel ball coal mills.

[0032] Advantages of the present invention:

[0033] (1) After the dual-source multi-fuel system designed by the present invention replaces the existing boiler coal pulverizing system, it broadens the applicable range of coal types: by designing the gas drying system, the temperature of the hot medium at the inlet of the coal mill is effectively increased, the drying capacity is increased, the primary air powder temperature required for boiler combustion is maintained, the safe combustion of the boiler is ensured, and it can be applicable to various coal types such as lignite with high moisture content, bituminous coal with high volatile content, and lean coal with low volatile content, reducing the procurement cost of power plant fuel and improving the profitability of the power plant.

[0034] (2) After the dual-source multi-fuel system designed by the present invention replaces the existing boiler coal pulverizing system, it eliminates the restriction of the existing boiler coal pulverizing system on the deep peak shaving capacity of the unit: different drying hot media for coal mills are adopted according to the characteristics of different coal types to maintain the drying output required by the coal pulverizing system, ensure the stable combustion of the boiler under deep peak shaving, and make the coal pulverizing system no longer a restrictive factor affecting the deep peak shaving capacity of the unit.

[0035] (3) After the dual-source multi-fuel system designed by the present invention replaces the existing boiler coal pulverizing system, it eliminates the restriction of the existing boiler coal pulverizing system on the rapid load change capacity of the coal-fired power unit: by setting up an independent coal powder bin and a powder bin burner, rapid fuel supply can be carried out for the coal-fired power unit, solving the problem of lag in fuel supply during the initial stage of rapid load increase of the coal-fired power unit and the initial stage of starting the coal mill, and making the coal pulverizing system no longer a restrictive factor affecting the rapid load change capacity of the unit.

[0036] (4) After the dual-source multi-fuel system designed by the present invention replaces the existing boiler coal pulverizing system, it overcomes the deflagration problem of the existing boiler coal pulverizing system and improves safety: The gas drying system designed by the present invention can use different pulverized coal conveying media according to the characteristics of different coal types to ensure that the entire system is in an inert atmosphere and avoid system deflagration. When burning high-volatile coal: The gas drying system designed by the present invention divides the first and second drying gas units into five paths respectively, so that a small part of the first and second drying gases can first be mixed with the third drying gas (flue gas) and enter the coal mill (including the coal storage mill and the main combustion mill) to dry the coal. At this time, since the flow rates of the first and second drying gases entering the coal mill are small, the problem of deflagration in the coal mill can be avoided. When the coal grinding is completed in the coal mill and the pulverized coal is transported to the pulverized coal burner by the first, second, and third drying gases, another path of the first and second drying gases arranged near the pulverized coal burner converges with it, causing the primary air powder (pulverized coal) entering the pulverized coal burner to heat up and increase the oxygen content, which is more conducive to combustion. If a large amount of the first and second drying gases and the third drying gas are directly introduced into the coal mill to dry and transport the coal, it is easy to cause the problem of system deflagration and low safety.

[0037] (5) For the dual-source multi-fuel system designed by the present invention, the outlet of the exhaust gas fan is also divided into two paths, one of which is connected to the inlet of the coal storage mill. In this way, part of the exhaust gas can be mixed with the drying gases (the first, second, and third drying gases) to dry and transport the coal in the coal storage mill, thereby further improving the drying and transportation effects. Or rather, since a part of the exhaust gas is introduced into the coal storage mill, the flow rates of the first, second, and third drying gases can also be appropriately reduced. Reducing the flow rate of the drying gases can also reduce the transportation energy consumption of the drying gases and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 is a schematic structural diagram of the boiler coal pulverizing system of an existing power plant;

[0040] Figure 2 is a schematic structural diagram of a dual-source multi-fuel system designed in Embodiment 1;

[0041] Figure 3 is a schematic structural diagram of a dual-source multi-fuel system designed in Embodiment 2. In order to simplify the schematic diagram, therefore, in Figure 3The connection mode between the gas drying system and the main coal-fired pulverizer is not shown in the figure, and the connection mode can be referred to Figure 2 ;

[0042] Figure 4 FIG. is a schematic structural diagram of a dual-source multi-fuel system designed for Embodiment 3. In order to simplify the schematic diagram, the connection mode between the gas drying system and the main coal-fired pulverizer is not shown in Figure 4 The connection mode between the gas drying system and the main coal-fired pulverizer is not shown in the figure, and the connection mode can be referred to Figure 2 ;

[0043] Figure 5 FIG. is a schematic structural diagram of a dual-source multi-fuel system designed for Embodiment 4. In order to simplify the schematic diagram, the connection mode between the gas drying system and the main coal-fired pulverizer is not shown in Figure 5 The connection mode between the gas drying system and the main coal-fired pulverizer is not shown in the figure, and the connection mode can be referred to Figure 2 .

[0044] Reference signs in the figure: 1 - boiler, 2 - main coal-fired pulverizer, 3 - coal storage pulverizer, 4 - fine powder separator, 5 - exhauster, 6 - coal powder silo, 7 - first drying gas unit, 8 - second drying gas unit, 9 - third drying gas unit, 10 - impeller feeder, 11 - exhauster burner, 12 - coal powder silo burner, 13 - air-coal powder burner, 14 - coal powder mixer. Detailed implementation manners

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is 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 orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0047] Embodiment 1

[0048] As Figure 2 shown, in this Embodiment 1, a dual-source multi-fuel system is designed, and the dual-source multi-fuel system includes the following structural settings:

[0049] A boiler 1, in which there is provided an exhaust gas burner 11, a pulverized coal bin burner 12, and two pulverized coal-air burners 13;

[0050] A main coal mill 2, which is used for grinding coal to produce pulverized coal, and the main coal mill 2 is communicatively connected to one of the pulverized coal-air burners 13 in the boiler 1;

[0051] A coal storage mill 3, which is used for grinding coal to produce pulverized coal, and the coal storage mill 3 is communicatively connected to the other pulverized coal-air burner 13 in the boiler 1;

[0052] A gas drying system, which includes a first drying gas unit 7, a second drying gas unit 8 and a third drying gas unit 9. The first drying gas unit 7 is divided into five paths (each of these five paths may also include several branches respectively). One path is directly connected to the coal storage and pulverizing mill 3. One path is arranged close to the upstream of the pulverized coal burner 13 connected to the coal storage and pulverizing mill 3. One path is connected to the subsequent hot medium coal powder feeding system. One path is connected to the main coal burner 2. The remaining one path is arranged close to the upstream of the pulverized coal burner 13 connected to the main coal burner 2. The second drying gas unit 8 is also divided into five paths. One path is directly connected to the coal storage and pulverizing mill 3. One path is arranged close to the upstream of the pulverized coal burner 13 connected to the coal storage and pulverizing mill 3. One path is connected to the hot medium coal powder feeding system. One path is connected to the main coal burner 2. The remaining one path is arranged close to the upstream of the pulverized coal burner 13 connected to the main coal burner 2. The third drying gas unit 9 is divided into three paths. One path is connected to the main coal burner 2, one path is connected to the coal storage and pulverizing mill 3, and the remaining one path is connected to the hot medium coal powder feeding system. The first and second drying gases in the first and second drying gas units 7 and 8 respectively come from this boiler 1 and / or the adjacent boiler 1. The first and second drying gases are respectively the hot primary air and cold primary air of the boiler. The third drying gas in the third drying gas unit 9 comes from this boiler 1 and / or the adjacent boiler 1. The third drying gas is the flue gas inside or at the outlet of the boiler. The gas drying system is used to dry the coal being ground in the main coal burner 2 and the coal storage and pulverizing mill 3, and to convey the pulverized coal generated after grinding in the coal storage and pulverizing mill 3 to the downstream equipment (fine powder separator 4) and the pulverized coal burner 13, and to convey the pulverized coal generated after grinding in the main coal burner 2 to the pulverized coal burner 13. The conveying process forms the primary air powder.

[0053] A fine powder separator 4, which is arranged downstream of the coal storage and pulverizing mill 3 and is connected to it, and is used to separate the primary air powder conveyed from the coal storage and pulverizing mill 3 to form pulverized coal and exhausted gas (the connecting pipeline between the coal storage and pulverizing mill 3 and the fine powder separator 4 can be led out from the equipment body of the coal storage and pulverizing mill 3).

[0054] An exhausted gas fan 5, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the exhausted gas generated in the fine powder separator 4. The outlet of the exhausted gas fan 5 is respectively connected to the exhausted gas burner 11 in the boiler 1 and the coal storage and pulverizing mill 3.

[0055] A coal powder silo 6, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the pulverized coal generated in the fine powder separator 4.

[0056] Hot medium powder feeding system, which includes an impeller powder feeder 10 and a pulverized coal mixer 14. The impeller powder feeder 10 is arranged downstream of the pulverized coal bin 6 and is communicated with it. The pulverized coal mixer 14 is arranged downstream of the impeller powder feeder 10 and is communicated with it. The impeller powder feeder 10 is used to convey the pulverized coal in the pulverized coal bin 6 into the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is communicated with the powder bin burner 12. The first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 are communicated with the pulverized coal mixer 14. By mixing the first, second and third drying gases in the first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 to form a hot medium and introducing it into the pulverized coal mixer 14, the pulverized coal to be conveyed to the powder bin burner 12 can be pre-heated (the pulverized coal in the pulverized coal bin 6 can be conveyed to the powder bin burner 12 through the combined action of the impeller powder feeder 10 and the first, second and third drying gases).

[0057] Specifically, in the above-mentioned Embodiment 1, after the hot primary air (the first drying gas) from the boiler is mixed with the cold primary air (the second drying gas), it is further mixed with the hot flue gas (the third drying gas) inside or discharged from the boiler. The formed mixed heat medium is sent into the main combustion coal mill 2 and the coal powder storage mill 3 to dry and convey the coal being ground in the main combustion coal mill 2 and the coal powder storage mill 3. After grinding and drying, primary air powder is formed. The primary air powder formed in the coal powder storage mill 3 is discharged from the upper part, mixed with the hot primary air and the cold primary air from the boiler, and then conveyed through a pipeline to the air powder burner 13 of the boiler 1 for combustion, providing heat for the boiler. The primary air powder formed in the main combustion coal mill 2 is discharged from the upper part, mixed with the hot primary air and the cold primary air from the boiler, and then conveyed through a pipeline to another air powder burner 13 of the boiler 1 for combustion, providing heat for the boiler. When it is necessary to store coal powder in the coal powder silo 6, the powder-making pipeline valve above the coal powder storage mill 3 is opened (this powder-making pipeline can be led out from the equipment body of the coal powder storage mill 3 or from the primary air powder pipeline at the outlet of the coal powder storage mill 3). The primary air powder formed in the coal powder storage mill 3 is conveyed through the powder-making pipeline to the fine powder separator 4 for air-powder separation, forming coal powder and exhausted gas. The coal powder enters the coal powder silo 6 for storage, and the exhausted gas enters the exhausted gas fan 5. The exhausted gas separated from the fine powder separator 4 is conveyed by the exhausted gas fan 5 in two paths. One path is sent to the exhausted gas burner 11 of the boiler 1 for combustion, providing heat for the boiler; the other path is sent through a pipeline to the inlet of the coal powder storage mill 3 to be recycled after being mixed with the first, second, and third drying gases. These two paths can be used simultaneously or either one of them can be used alone. When it is necessary to use the coal powder in the coal powder silo 6 for the combustion of the boiler 1, the coal powder in the coal powder silo 6 is conveyed to the coal powder mixer 14 through the impeller feeder 10. The hot primary air from the boiler is mixed with the cold primary air, and then further mixed with the hot flue gas inside or discharged from the boiler to form a heat medium. The heat medium is conveyed through a pipeline to the coal powder mixer 14. In the coal powder mixer 14, the heat medium is mixed with the coal powder, and then enters the powder silo burner 12 of the boiler 1 through the powder conveying pipeline for combustion, providing heat for the boiler.

[0058] Since the primary air powder concentration output within the first 5 to 10 minutes after the main coal mill 2 starts running is relatively low, there is a problem that the pulverized coal burners 13 connected to the main coal mill 2 in the boiler 1 cannot be ignited and burned. The pulverized coal bunker burner 12 provided in Embodiment 1 can compensate for the insufficient heat input caused by the inability of the pulverized coal burners 13 in the boiler 1 to burn, and can solve the problem that the pulverized coal burners 13 cannot burn within the first 5 to 10 minutes of starting operation. This is beneficial to the rapid load change of the coal-fired power unit, improves the operation flexibility of the coal-fired power unit under complex coal quality conditions, solves the problem of fuel supply. When the coal-fired power unit increases the load, this dual-source multi-burner system designed in Embodiment 1 can quickly add sufficient fuel (pulverized coal) to the pulverized coal bunker burner 12 (equivalent to the boiler) for combustion through the replenishment of the pulverized coal bunker 6. It overcomes the drawback of the existing boiler coal pulverizing system that the fuel increase has a lag. Therefore, after the coal-fired power unit receives the fuel increase command, the boiler can immediately produce the air-powder that meets the combustion concentration requirements, greatly improving the operation flexibility of the coal-fired power unit and enhancing the rapid load change rate of the unit.

[0059] Embodiment 2

[0060] As Figure 3 shown, this Embodiment 2 designs a dual-source multi-burner system, and this dual-source multi-burner system includes the following structural settings:

[0061] A boiler 1, which is provided with a lean gas burner 11, two pulverized coal bunker burners 12, and three pulverized coal burners 13;

[0062] A main coal mill 2, which is used for grinding coal to produce pulverized coal, and the main coal mill 2 is connected to one of the pulverized coal burners 13 in the boiler 1;

[0063] Two coal storage and grinding mills 3, which are used for grinding coal to produce pulverized coal, and the two coal storage and grinding mills 3 are respectively connected to the other two pulverized coal burners 13 in the boiler 1;

[0064] A gas drying system, which includes a first drying gas unit 7, a second drying gas unit 8 and a third drying gas unit 9. The first drying gas unit 7 is divided into five paths (each of these five paths may also include several branches respectively). One path is respectively connected to two coal pulverizers 3. One path is respectively arranged close to the upstream of two pulverized coal burners 13 which are respectively connected to the two coal pulverizers 3. One path is connected to the subsequent hot medium coal powder feeding system. One path is connected to the main coal burner 2. The remaining one path is arranged close to the upstream of the pulverized coal burner 13 which is connected to the main coal burner 2. The second drying gas unit 8 is also divided into five paths. One path is respectively connected to two coal pulverizers 3. One path is respectively arranged close to the upstream of two pulverized coal burners 13 which are respectively connected to the two coal pulverizers 3. One path is connected to the hot medium coal powder feeding system. One path is connected to the main coal burner 2. The remaining one path is arranged close to the upstream of the pulverized coal burner 13 which is connected to the main coal burner 2. The third drying gas unit 9 is divided into three paths. One path is connected to the main coal burner 2. One path is respectively connected to two coal pulverizers 3. The remaining one path is connected to the hot medium coal powder feeding system. The first and second drying gases in the first and second drying gas units 7 and 8 respectively come from this boiler 1 and / or the adjacent boiler 1. The first and second drying gases are respectively the primary hot air and the primary cold air of the boiler. The third drying gas in the third drying gas unit 9 comes from this boiler 1 and / or the adjacent boiler 1. The third drying gas is the flue gas inside or at the outlet of the boiler. The gas drying system is used to dry the coal being ground in the main coal burner 2 and the coal pulverizers 3, and is used to respectively convey the pulverized coal generated after grinding in the two coal pulverizers 3 to the downstream equipment (fine powder separator 4) and the two pulverized coal burners 13, and convey the pulverized coal generated after grinding in the main coal burner 2 to the pulverized coal burner 13, and the conveying process forms the primary air powder mixture.

[0065] A fine powder separator 4, which is arranged downstream of the coal pulverizer 3 and is connected to it (the two coal pulverizers 3 share one fine powder separator 4). The fine powder separator 4 is used to separate the primary air powder mixture conveyed from the coal pulverizer 3 to form pulverized coal and exhausted gas (the connecting pipeline between the coal pulverizer 3 and the fine powder separator 4 can be led out from the equipment body of the coal pulverizer 3).

[0066] An exhausted gas fan 5, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the exhausted gas generated in the fine powder separator 4. The outlet of the exhausted gas fan 5 is respectively connected to the exhausted gas burner 11 in the boiler 1 and the two coal pulverizers 3.

[0067] A coal powder silo 6, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the pulverized coal generated in the fine powder separator 4.

[0068] A hot medium powder feeding system, which includes an impeller feeder 10 and a pulverized coal mixer 14. The impeller feeder 10 is arranged downstream of the pulverized coal bin 6 and communicated with it. The pulverized coal mixer 14 is arranged downstream of the impeller feeder 10 and communicated with it. The impeller feeder 10 is used to convey the pulverized coal in the pulverized coal bin 6 into the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is respectively communicated with two bin burners 12. The first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 are communicated with the pulverized coal mixer 14. By mixing the first, second and third drying gases in the first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 and introducing them into the pulverized coal mixer 14, the pulverized coal to be conveyed to the bin burner 12 can be preheated (the pulverized coal in the pulverized coal bin 6 can be conveyed to the bin burner 12 through the combined action of the impeller feeder 10 and the first, second and third drying gases).

[0069] Specifically, the difference between the above-mentioned embodiment 2 and embodiment 1 is that: in embodiment 2, the installation quantities of the coal storage and grinding mill 3, the bin burner 12 and the air-powder burner 13 are different from those in embodiment 1, but the principles are the same. The two coal storage and grinding mills 3 in embodiment 2 can be used simultaneously or separately. The air-powder burners 13 correspondingly arranged with the coal storage and grinding mills 3 are used simultaneously or separately according to the usage situation of the coal storage and grinding mills 3. The two bin burners 12 in embodiment 2 can be used for combustion simultaneously or only one of them can be operated.

[0070] Embodiment 3

[0071] As Figure 4 shown, this embodiment 3 designs a dual-source multi-fuel combustion system, and this dual-source multi-fuel combustion system includes the following structural settings:

[0072] A boiler 1, in which there are two exhaust gas burners 11, one bin burner 12 and three air-powder burners 13;

[0073] A main combustion coal grinding mill 2, which is used for grinding coal to produce pulverized coal, and the main combustion coal grinding mill 2 is communicated with one of the air-powder burners 13 in the boiler 1;

[0074] Two coal storage and grinding mills 3, which are used for grinding coal to produce pulverized coal, and the two coal storage and grinding mills 3 are respectively communicated with the other two air-powder burners 13 in the boiler 1;

[0075] A gas drying system, which includes a first drying gas unit 7, a second drying gas unit 8 and a third drying gas unit 9. The first drying gas unit 7 is divided into five paths (each of these five paths may also include several branches respectively). One path is respectively connected to two coal storage and pulverizing mills 3; one path is respectively arranged close to the upstream of two pulverized coal burners 13 which are respectively connected to the two coal storage and pulverizing mills 3; one path is connected to the subsequent hot medium coal powder feeding system; one path is connected to the main coal burner 2; and the remaining one path is arranged close to the upstream of the pulverized coal burner 13 which is connected to the main coal burner 2. The second drying gas unit 8 is also divided into five paths. One path is respectively connected to two coal storage and pulverizing mills 3; one path is respectively arranged close to the upstream of two pulverized coal burners 13 which are respectively connected to the two coal storage and pulverizing mills 3; one path is connected to the hot medium coal powder feeding system; one path is connected to the main coal burner 2; and the remaining one path is arranged close to the upstream of the pulverized coal burner 13 which is connected to the main coal burner 2. The third drying gas unit 9 is divided into three paths. One path is connected to the main coal burner 2, one path is respectively connected to two coal storage and pulverizing mills 3, and the remaining one path is connected to the hot medium coal powder feeding system. The first and second drying gases in the first and second drying gas units 7 and 8 respectively come from this boiler 1 and / or an adjacent boiler 1, and the first and second drying gases are respectively the hot primary air and cold primary air of the boiler. The third drying gas in the third drying gas unit 9 comes from this boiler 1 and / or an adjacent boiler 1, and the third drying gas is the flue gas inside or at the outlet of the boiler. The gas drying system is used to dry the coal being ground in the main coal burner 2 and the coal storage and pulverizing mills 3, and to respectively convey the pulverized coal generated after grinding in the two coal storage and pulverizing mills 3 to two fine powder separators 4 and two pulverized coal burners 13, and convey the pulverized coal generated after grinding in the main coal burner 2 to the pulverized coal burner 13, and a primary air-pulverized coal mixture is formed during the conveying process.

[0076] Two fine powder separators 4, which are respectively arranged downstream of the two coal storage and pulverizing mills 3 and are connected thereto. The two coal storage and pulverizing mills 3 are respectively connected to the two fine powder separators 4. The two fine powder separators 4 are used to separate the primary air-pulverized coal mixture conveyed from the two coal storage and pulverizing mills 3 to form pulverized coal and exhausted gas (the connecting pipeline between the coal storage and pulverizing mill 3 and the fine powder separator 4 can be led out from the equipment body of the coal storage and pulverizing mill 3).

[0077] An exhausted gas fan 5, which is arranged downstream of the two fine powder separators 4 and is connected thereto (the two fine powder separators 4 share one exhausted gas fan 5), is used to collect the exhausted gas generated in the fine powder separators 4. The outlet of the exhausted gas fan 5 is respectively connected to two exhausted gas burners 11 in the boiler 1 and the two coal storage and pulverizing mills 3.

[0078] A pulverized coal bin 6 is arranged downstream of the fine powder separator 4 and communicated with the fine powder separator 4 for collecting pulverized coal generated in the fine powder separator 4;

[0079] A hot medium powder feeding system includes a vane feeder 10 and a pulverized coal mixer 14. The vane feeder 10 is arranged downstream of the pulverized coal bin 6 and communicated with the pulverized coal bin 6. The pulverized coal mixer 14 is arranged downstream of the vane feeder 10 and communicated with the vane feeder 10. The vane feeder 10 is used for conveying the pulverized coal in the pulverized coal bin 6 to the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is communicated with a bin burner 12. The first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 are communicated with the pulverized coal mixer 14. By mixing the first, second and third drying gases in the first drying gas unit 7, the second drying gas unit 8 and the third drying gas unit 9 and introducing them into the pulverized coal mixer 14, the pulverized coal to be conveyed to the bin burner 12 can be preheated (the pulverized coal in the pulverized coal bin 6 can be conveyed to the bin burner 12 through the combined action of the vane feeder 10 and the first, second and third drying gases).

[0080] Example 4

[0081] As Figure 5 shown, in this Example 4, a dual-source multi-fuel combustion system is designed, and the dual-source multi-fuel combustion system includes the following structural settings:

[0082] A boiler 1 is provided with a lean gas burner 11, a bin burner 12 and two air-powder burners 13;

[0083] A main combustion pulverizer 2 is used for pulverizing coal to generate pulverized coal, and the main combustion pulverizer 2 is communicated with one of the air-powder burners 13 in the boiler 1;

[0084] A powder storage pulverizer 3 is used for pulverizing coal to generate pulverized coal, and the powder storage pulverizer 3 is communicated with the other air-powder burner 13 in the boiler 1;

[0085] A gas drying system, which includes a first drying gas unit 7 and a second drying gas unit 8. The first drying gas unit 7 is divided into three paths (several branch paths may also be included in these three paths respectively). One path is directly connected to the pulverized coal storage and grinding mill 3, one path is connected to the subsequent hot medium coal powder feeding system, and the remaining one path is connected to the main combustion pulverized coal mill 2. The second drying gas unit 8 is also divided into three paths. One path is directly connected to the pulverized coal storage and grinding mill 3, one path is connected to the hot medium coal powder feeding system, and the remaining one path is connected to the main combustion pulverized coal mill 2. The first and second drying gases in the first and second drying gas units 7 and 8 respectively come from this boiler 1 and / or an adjacent boiler 1, and the first and second drying gases are respectively the hot primary air and cold primary air of the boiler. The gas drying system is used to dry the coal being ground in the main combustion pulverized coal mill 2 and the pulverized coal storage and grinding mill 3, and to transport the pulverized coal generated after grinding in the pulverized coal storage and grinding mill 3 to downstream equipment (fine powder separator 4) and the pulverized coal-air burner 13, and to transport the pulverized coal generated after grinding in the main combustion pulverized coal mill 2 to the pulverized coal-air burner 13. During the transportation process, primary air-powder is formed.

[0086] A fine powder separator 4, which is arranged downstream of the pulverized coal storage and grinding mill 3 and is connected to it, is used to separate the primary air-powder transported from the pulverized coal storage and grinding mill 3 to form pulverized coal and exhausted gas.

[0087] An exhausted gas fan 5, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the exhausted gas generated in the fine powder separator 4. The outlet of the exhausted gas fan 5 is respectively connected to the exhausted gas burner 11 in the boiler 1 and the pulverized coal storage and grinding mill 3.

[0088] A pulverized coal bin 6, which is arranged downstream of the fine powder separator 4 and is connected to it, is used to collect the pulverized coal generated in the fine powder separator 4.

[0089] A hot medium coal powder feeding system, which includes an impeller coal feeder 10 and a coal powder mixer 14. The impeller coal feeder 10 is arranged downstream of the pulverized coal bin 6 and is connected to it. The coal powder mixer 14 is arranged downstream of the impeller coal feeder 10 and is connected to it. The impeller coal feeder 10 is used to transport the pulverized coal in the pulverized coal bin 6 to the coal powder mixer 14. The outlet of the coal powder mixer 14 is connected to the pulverized coal bin burner 12. The first drying gas unit 7 and the second drying gas unit 8 are connected to the coal powder mixer 14. By mixing the first and second drying gases in the first drying gas unit 7 and the second drying gas unit 8 and introducing them into the coal powder mixer 14, the pulverized coal to be transported to the pulverized coal bin burner 12 can be preheated (the pulverized coal in the pulverized coal bin 6 can be transported to the pulverized coal bin burner 12 through the combined action of the impeller coal feeder 10 and the first and second drying gases).

[0090] The difference between the dual-source multi-fuel system designed in the above-mentioned Embodiment 4 and Embodiment 1 lies in that: in the gas drying system of Embodiment 4, the third drying gas unit 9 is not provided, and the first and second drying gas units 7 and 8 in Embodiment 4 are arranged in three paths, which is different from the five-path arrangement in Embodiment 1, and the rest is the same as that in Embodiment 1.

[0091] For coal types with low volatile matter, the drying gas may not use flue gas (the third drying gas), and only use the hot primary air (the first drying gas) and the cold primary air (the second drying gas) of the boiler. Therefore, the third drying gas 9 is not provided in the dual-source multi-fuel system of Embodiment 4; at the same time, since the third drying gas (flue gas) in the system of Embodiment 4 is missing for drying and conveying the coal in the main coal mill 2 and the coal powder storage mill 3, the amount of the first and second drying gases introduced into the main coal mill 2 and the coal powder storage mill 3 can be increased (that is, the five-path arrangement of the first and second drying gas units 7 and 8 in Embodiment 1 is changed to a three-path arrangement in Embodiment 4). This is not only beneficial to the drying of the coal in the coal mill and the conveying of the pulverized coal after grinding, but also because the third drying gas is not introduced into the main coal mill 2 and the coal powder storage mill 3, the wear of the equipment by the third drying gas can be avoided, thereby avoiding the reduction of the service life of the equipment and affecting the reliability of the equipment operation.

[0092] The above are the preferred embodiments of the present invention, which are only used to explain the present invention and are not used to limit the present invention. Any obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A dual-source multi-fuel system, characterized in that, The dual-source multi-fuel system includes the following structural settings: A boiler (1), in which there are provided at least one lean gas burner (11), at least one pulverized coal bin burner (12), and at least two pulverized coal-air burners (13); A number of main coal mills (2) for grinding coal to produce pulverized coal, and the main coal mills (2) are communicatively connected to one or several pulverized coal-air burners (13) in the boiler (1); A number of coal storage mills (3) for grinding coal to produce pulverized coal, and the number of coal storage mills (3) are respectively communicatively connected to the remaining pulverized coal-air burners (13) in the boiler (1); A gas drying system, which is respectively communicatively connected to the main coal mills (2) and the coal storage mills (3), and the gas drying system is used for drying the coal ground in the main coal mills (2) and the coal storage mills (3), and for transporting the pulverized coal produced after grinding to downstream equipment and the pulverized coal-air burners (13), and a primary pulverized coal-air mixture is formed during the transportation process; A number of fine powder separators (4), which are arranged downstream of the coal storage mills (3) and communicatively connected thereto, for separating the primary pulverized coal-air mixture transported from the coal storage mills (3) to form pulverized coal and lean gas; A number of lean gas blowers (5), which are arranged downstream of the fine powder separators (4) and communicatively connected thereto, for collecting the lean gas generated in the fine powder separators (4), and the outlets of the lean gas blowers (5) are respectively communicatively connected to the lean gas burners (11) in the boiler (1) and the coal storage mills (3); A number of pulverized coal bins (6), which are arranged downstream of the fine powder separators (4) and communicatively connected thereto, for collecting the pulverized coal generated in the fine powder separators (4); A hot medium coal feeding system, which is arranged downstream of the pulverized coal bins (6) and communicatively connected thereto, for transporting the pulverized coal in the pulverized coal bins (6) to the pulverized coal bin burners (12), and the gas drying system is also communicatively connected to the hot medium coal feeding system for preheating the pulverized coal transported to the pulverized coal bin burners (12).

2. The dual-source multi-fuel system according to claim 1, characterized in that, The number of the pulverized coal-air burners (13) may be the same as or different from the sum of the numbers of the main coal mills (2) and the coal storage mills (3).

3. A dual-source multi-fuel system according to claim 1, characterized in that, The number of the fine powder separators (4) may be the same as or different from the number of the coal storage mills (3).

4. A dual-source multi-fuel system according to claim 1, wherein, The gas drying system includes: a first drying gas unit (7) and a second drying gas unit (8); the gas drying system may also include or not include a third drying gas unit (9); Wherein, the first drying gas unit (7) is respectively communicatively connected to a number of main coal mills (2), a number of coal storage mills (3), and the hot medium coal feeding system; The second drying gas unit (8) is respectively communicatively connected to a number of main coal mills (2), a number of coal storage mills (3), and the hot medium coal feeding system; The third drying gas unit (9) is respectively communicatively connected to a number of main coal mills (2), a number of coal storage mills (3), and the hot medium coal feeding system.

5. A dual-source multi-fuel system according to claim 4, characterized in that, The first drying gas unit (7) is divided into five paths. One path is directly connected to several coal powder storage and grinding mills (3) respectively. One path is arranged close to the upstream of the pulverized coal burner (13) connected to the coal powder storage and grinding mill (3). One path is connected to the hot medium coal powder feeding system. One path is connected to several main combustion coal grinding mills (2). The remaining path is arranged close to the upstream of the pulverized coal burner (13) connected to the main combustion coal grinding mill (2). The second drying gas unit (8) is divided into five paths. One path is directly connected to several coal powder storage and grinding mills (3) respectively. One path is arranged close to the upstream of the pulverized coal burner (13) connected to the coal powder storage and grinding mill (3). One path is connected to the hot medium coal powder feeding system. One path is connected to several main combustion coal grinding mills (2). The remaining path is arranged close to the upstream of the pulverized coal burner (13) connected to the main combustion coal grinding mill (2).

6. A dual-source multi-fuel system according to claim 4 or 5, characterized in that, The first drying gas in the first drying gas unit (7) comes from this boiler (1) and / or the adjacent boiler (1), and the first drying gas is the primary hot air of the boiler. The second drying gas in the second drying gas unit (8) comes from this boiler (1) and / or the adjacent boiler (1), and the second drying gas is the primary cold air of the boiler. The third drying gas in the third drying gas unit (9) comes from this boiler (1) and / or the adjacent boiler (1), and the third drying gas is the flue gas inside or at the outlet of the boiler.

7. A dual-source multi-fuel system according to claim 6, characterized in that, Whether to include or not include the third drying gas unit (9) in the gas drying system is set according to the volatile matter of the ground coal in the main combustion coal grinding mill (2) and the coal powder storage and grinding mill (3). For coal with low volatile matter, the third drying gas unit (9) is not set, and vice versa.

8. A dual-source multi-fuel system according to claim 1, wherein, The hot medium coal powder feeding system includes: several impeller coal feeders (10) and several coal powder mixers (14). The impeller coal feeder (10) is arranged downstream of the coal powder bin (6) and is connected to it. The coal powder mixer (14) is arranged downstream of the impeller coal feeder (10) and is connected to it. The impeller coal feeder (10) is used to convey the coal powder in the coal powder bin (6) to the coal powder mixer (14), and the outlet of the coal powder mixer (14) is connected to the bin burner (12).

9. A dual-source multi-fuel system according to claim 8, characterized in that, The gas drying system is connected to the inlet of the coal powder mixer (14).

10. A dual-source multi-fuel system according to any one of claims 1 to 9, characterized in that, The main combustion coal grinding mill (2) and the coal powder storage and grinding mill (3) are respectively selected from medium-speed coal grinding mills or double-in and double-out steel ball coal grinding mills.

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