A dual-source multi-fuel system

Abstract

This utility model discloses a dual-source multi-combustion system, comprising: a boiler, wherein an exhaust gas burner, a pulverized coal silo burner, and at least two air-coal burners are provided; a plurality of main combustion coal mills are connected to one or more air-coal burners; a plurality of pulverized coal storage mills are connected to the remaining air-coal burners in the boiler; a gas drying system is connected to the main combustion coal mills and the pulverized coal storage mills respectively, for drying and conveying the coal ground in the main combustion coal mills and the pulverized coal storage mills to form primary air-coal mixture; a plurality of fine powder separators are used to separate the primary air-coal mixture to form pulverized coal and exhaust gas; a plurality of exhaust gas fans are used to collect exhaust gas, and the outlets of the exhaust gas fans are connected to the exhaust gas burner and the pulverized coal storage mill respectively; a plurality of pulverized coal silos are used to collect the pulverized coal generated in the fine powder separators; a hot medium conveying system is used to convey the pulverized coal in the pulverized coal silos to the pulverized coal silo burners, and the gas drying system is also connected to the hot medium conveying system to preheat the pulverized coal conveyed to the pulverized coal silo burners.

Description

Technical Field

[0001] This utility model relates to the field of thermal power generation technology, specifically to a dual-source multi-fuel system. Background Technology

[0002] Coal price fluctuations are crucial to the profits of coal-fired power units, and the prices of different types of coal vary greatly. To reduce costs, power plants often blend large quantities of economical coal types such as high-moisture lignite and low-volatile lean coal, resulting in an increasingly wide range of coal types used by power plants, often exceeding the applicability of existing boiler pulverizing systems.

[0003] Furthermore, in building a new power system with new energy as the mainstay, the positioning of new energy as the primary power source has been clearly defined, and the role of coal-fired power has undergone a fundamental transformation, shifting from a primary power source to a basic guarantee and system regulation power source providing reliable capacity, peak shaving, frequency regulation, and other ancillary services. During this stage, the policy environment is based on the "dual carbon" goal and energy security, emphasizing deep peak shaving, rapid load change, and high efficiency across wide load ranges for coal-fired power units. As the power grid continuously increases the peak shaving depth and rapid load change rate of coal-fired power units, the traditional boiler pulverizing system of coal-fired power units is struggling to meet this requirement (the working principle of the boiler pulverizing system is that raw coal is fed into the pulverizer of the pulverizing system, ground and dried into pulverized coal, and then fed into the boiler burner for combustion, providing heat input to the boiler).

[0004] Existing power plant boiler pulverizing systems mostly adopt medium-speed coal mill direct-fired pulverizing systems, such as... Figure 1 As shown, hot primary air and cold primary air from the boiler are mixed, and the resulting mixture is sent to coal mill A and coal mill B respectively to dry and transport the coal being ground in coal mill A and coal mill B. After drying, it forms primary air pulverized coal. The primary air pulverized coal formed in coal mills A and B is discharged from the top of the coal mills and transported through pipelines to the primary air pulverized coal burners A and B of the boiler for combustion, providing heat to the boiler. Each boiler is usually equipped with two or more coal mills and related inlet and outlet pipelines, and each coal mill can operate independently.

[0005] However, the current boiler pulverizing system has the following disadvantages: (1) Limited range of coal types: It is usually only suitable for bituminous coal with high volatile matter and low moisture content, and not suitable for lignite with high moisture content. Due to the limitation of the hot air temperature at the inlet of the coal mill (usually below 300℃), the drying output of the original pulverizing system is limited and cannot completely dry lignite with high moisture content. As a result, the primary air-coal temperature at the outlet of the coal mill is too low and cannot meet the requirements for stable combustion of the boiler. This limits the range of coal types that the power plant can use and affects the economic benefits of the power plant; (2) Not conducive to deep peak shaving operation of coal-fired power units: When the unit is in 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℃ when the unit load is 20%). The drying output of the coal mill is severely restricted, resulting in the primary air-coal temperature at the outlet of the coal mill being much lower than the conventional 70℃. This affects the stable combustion of the boiler and the deep peak shaving operation. (3) It is not conducive to the rapid load change of coal-fired power units: To improve the flexibility of unit operation under complex coal quality conditions, the first thing to do is to solve the problem of fuel supply. When the unit load increases, the pulverizing system should be able to quickly increase enough fuel (coal powder). However, the existing pulverizing system has the disadvantage of fuel increase being delayed. It usually takes 5 to 10 minutes from the time the coal-fired power unit receives the fuel increase instruction to the time the primary air-coal burner outlet of the boiler produces primary air-coal that meets the combustion concentration requirements, which seriously affects the rapid load change rate of the coal-fired power unit. (4) The pulverizing system has the risk of deflagration, which affects safety: Since the existing boiler pulverizing system is only suitable for bituminous coal, and bituminous coal has a high volatile content, it is easy to cause deflagration in the pulverizing system. Especially under the deep peak shaving of the unit, the power plant tends to burn coal with high volatile content to ensure the stable combustion of the boiler, which further aggravates the risk of deflagration. Utility Model Content

[0006] The purpose of this invention is to address the above-mentioned problems existing in existing boiler pulverizing systems by designing a dual-source, multi-fuel system to solve these problems.

[0007] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0008] This utility model designs a dual-source multi-fuel system, which includes the following structural configuration:

[0009] A boiler, wherein at least one exhaust gas burner, at least one pulverized coal burner, and at least two air-coal burners are provided;

[0010] Several main-fired coal mills are used to grind coal to produce pulverized coal, and the main-fired coal mills are connected in communication with one or more air-coal burners in the boiler.

[0011] Several pulverized coal mills are used to grind coal to produce pulverized coal, and the pulverized coal mills are respectively connected to the remaining air-coal burners in the boiler.

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

[0013] Several fine powder separators are located downstream of and connected to the pulverized coal storage mill, and are used to separate the primary air and pulverized coal conveyed from the pulverized coal storage mill to form pulverized coal and exhaust gas.

[0014] Several exhaust gas blowers are installed downstream of and connected to the fine powder separator to collect the exhaust gas generated in the fine powder separator. The outlets of the exhaust gas blowers are respectively connected to the exhaust gas burner in the boiler and the pulverized coal mill.

[0015] Several coal powder bins are located downstream of and connected to the fine powder separator for collecting coal powder generated in the fine powder separator;

[0016] A hot medium conveying system is located downstream of and connected to the pulverized coal silo, and is used to convey pulverized coal in the pulverized coal silo to the pulverized coal silo burner. The gas drying system is also connected to the hot medium conveying system and is used to preheat the pulverized coal conveyed to the pulverized coal silo burner.

[0017] Specifically, the connection from the pulverized coal mill to the fine powder separator can be led out from the main body of the pulverized coal mill or from the main outlet pipe of the pulverized coal mill.

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

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

[0020] Furthermore, a dual-source multi-fuel 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] The first drying gas unit is connected to several main combustion coal mills, several coal storage mills and a hot medium coal conveying system respectively.

[0022] The second drying gas unit is connected to several main combustion coal mills, several pulverized coal mills, and a hot medium pulverized coal delivery system, respectively.

[0023] The third drying gas unit is connected to several main combustion coal mills, several coal storage mills, and a hot medium coal conveying system.

[0024] Furthermore, a dual-source, multi-fuel system is provided: the first drying gas unit is divided into five paths, one of which is directly connected to several pulverized coal mills, one is located upstream of the pulverized coal burner connected to the pulverized coal mills, one is connected to the heat medium pulverized coal delivery system, one is connected to several main-fuel coal mills, and the remaining path is located upstream of the pulverized coal burner connected to the main-fuel coal mills; the second drying gas unit is also divided into five paths, one of which is directly connected to several pulverized coal mills, one is located upstream of the pulverized coal burner connected to the pulverized coal mills, one is connected to the heat medium pulverized coal delivery system, one is connected to several main-fuel coal mills, and the remaining path is located upstream of the pulverized coal burner connected to the main-fuel coal mills.

[0025] Specifically, the third drying gas unit is divided into three paths, one of which is directly connected to several coal storage mills, another is connected to the hot medium coal conveying system, and the remaining path is connected to several main combustion mills.

[0026] Furthermore, a dual-source multi-fuel system is provided: the first dry gas in the first dry gas unit comes from the boiler itself and / or an adjacent boiler, and the first dry gas is the boiler's hot primary air; the second dry gas in the second dry gas unit comes from the boiler itself and / or an adjacent boiler, and the second dry gas is the boiler's cold primary air; the third dry gas in the third dry gas unit comes from the boiler itself and / or an adjacent boiler, and the third dry gas is the flue gas inside or at the outlet of the boiler.

[0027] Furthermore, a dual-source, multi-fuel system is proposed: the gas drying system may or may not include a third drying gas unit, depending on the volatile matter content of the coal ground in the main combustion coal mill and the pulverized coal mill; for coal with low volatile matter content, the third drying gas unit is not provided, and vice versa.

[0028] Furthermore, a dual-source multi-combustion system is provided: the heat medium pulverized coal feeding system includes: several impeller feeders and several pulverized coal mixers; the impeller feeders are located downstream of and connected to the pulverized coal silo, the pulverized coal mixers are located downstream of and connected to the impeller feeders, the impeller feeders are used to transport pulverized coal from the pulverized coal silo to the pulverized coal mixers, and the outlet of the pulverized coal mixers is connected to the silo burner.

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

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

[0031] Furthermore, a dual-source, multi-fuel system is provided: the main combustion coal mill and the pulverized coal storage mill are respectively selected as medium-speed coal mills or double-inlet, double-outlet ball mills.

[0032] The beneficial effects of this utility model are:

[0033] (1) The dual-source multi-combustion system designed in this utility model, after replacing the existing boiler pulverizing system, broadens the applicable range of coal types: by designing a gas drying system, the temperature of the heat medium at the inlet of the coal mill is effectively increased, the drying capacity is increased, the primary air-coal temperature that meets the combustion requirements of the boiler is maintained, and the safe combustion of the boiler is guaranteed. It can be applied to a variety of coal types such as high-moisture lignite, high-volatile bituminous coal, and low-volatile lean coal, thereby reducing the fuel procurement cost of the power plant and improving the profitability of the power plant.

[0034] (2) The dual-source multi-combustion system designed in this utility model replaces the existing boiler pulverizing system, which eliminates the constraint of the existing boiler pulverizing system on the deep peak shaving capacity of the unit: different coal mill drying heat media are used according to the characteristics of different coal types to maintain the drying output required by the pulverizing system, ensure the stable combustion of the boiler under deep peak shaving, and make the pulverizing system no longer a constraint on the deep peak shaving capacity of the unit.

[0035] (3) The dual-source multi-fuel system designed in this utility model replaces the existing boiler pulverizing system and eliminates the constraint of the existing boiler pulverizing system on the rapid load change capability of coal-fired power units: by setting up an independent pulverized coal silo and pulverized coal silo burner, the coal-fired power units can be supplied with fuel quickly, solving the problem of delayed fuel supply in the early stage of rapid load increase of coal-fired power units and the early stage of starting the coal mill, so that the pulverizing system is no longer a constraint on the rapid load change capability of the unit.

[0036] (4) This utility model's dual-source multi-combustion system, after replacing the existing boiler pulverizing system, overcomes the deflagration problem of the existing boiler pulverizing system and improves safety: The gas drying system designed in this utility model can use different coal powder conveying media according to the characteristics of different coal types, ensuring that the entire system is in an inert atmosphere and avoiding deflagration. When burning coal with high volatile content: The gas drying system designed in this utility model divides the first and second drying gas units into five paths respectively, so that a small portion of the first and second drying gases can be mixed with the third drying gas (flue gas) before entering the coal mill (including the storage coal mill and the main combustion coal mill) to dry the coal. At this time, since the flow rate of the first and second drying gases entering the coal mill is small, the problem of deflagration in the coal mill can be avoided. When the coal is pulverized in the coal mill and the coal powder is conveyed to the air-coal burner through the first, second and third drying gases, another path of the first and second drying gases set near the air-coal burner merges with it, causing the primary air-coal powder (coal powder) entering the air-coal burner to heat up and increase the oxygen content, which is more conducive to combustion. If large amounts of the first, second, and third drying gases are directly introduced into the coal mill to dry and transport the coal, it can easily cause system deflagration, resulting in low safety.

[0037] (5) The dual-source multi-fuel system designed in this utility model further divides the outlet of the exhaust gas fan into two paths, one of which is connected to the inlet of the pulverized coal mill. This allows some of the exhaust gas to mix with the drying gases (first, second, and third drying gases) to dry and transport the coal in the pulverized coal mill, thereby further improving the drying and transporting effect. Alternatively, since a portion of the exhaust gas is introduced into the pulverized coal mill, the flow rates of the first, second, and third drying gases can be appropriately reduced. The reduced flow rate of the drying gases can also reduce the energy consumption for transporting the drying gases, saving costs. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of an existing power plant's boiler pulverizing system;

[0040] Figure 2 This is a schematic diagram of the structure of a dual-source multi-fuel system designed in Example 1;

[0041] Figure 3 This is a structural schematic diagram of a dual-source multi-fuel system designed for Example 2. To simplify the schematic diagram, therefore... Figure 3The connection method between the gas drying system and the main combustion coal mill is not shown in the diagram; however, the connection method can be found by referring to [reference needed]. Figure 2 ;

[0042] Figure 4 This is a structural schematic diagram of a dual-source multi-fuel system designed in Example 3. To simplify the schematic diagram, therefore... Figure 4 The connection method between the gas drying system and the main combustion coal mill is not shown in the diagram; however, the connection method can be found by referring to [reference needed]. Figure 2 ;

[0043] Figure 5 This is a structural schematic diagram of a dual-source multi-fuel system designed in Example 4. To simplify the schematic diagram, therefore... Figure 5 The connection method between the gas drying system and the main combustion coal mill is not shown in the diagram; however, the connection method can be found by referring to [reference needed]. Figure 2 .

[0044] The diagram is labeled as follows: 1-Boiler, 2-Main combustion coal mill, 3-Pulverized coal mill, 4-Fine powder separator, 5-Exhaust gas fan, 6-Pulverized coal silo, 7-First drying gas unit, 8-Second drying gas unit, 9-Third drying gas unit, 10-Impeller feeder, 11-Exhaust gas burner, 12-Pulverized coal silo burner, 13-Air-coal burner, 14-Pulverized coal mixer. Detailed Implementation

[0045] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0046] In the description of this utility model, it should be understood that the terms "upper," "lower," "left," "right," "top," and "bottom," etc., indicating orientation or positional relationships, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this utility model described herein can be implemented in orders other than those illustrated or described herein.

[0047] Example 1

[0048] like Figure 2 As shown, this embodiment 1 designs a dual-source multi-fuel system, which includes the following structural configuration:

[0049] Boiler 1, which is equipped with one exhaust gas burner 11, one pulverized coal burner 12 and two air-coal burners 13;

[0050] A main combustion coal mill 2 is used to grind coal to produce pulverized coal, and the main combustion coal mill 2 is connected to a pulverized coal burner 13 in the boiler 1;

[0051] A pulverized coal mill 3 is used to grind coal to produce pulverized coal, and the pulverized coal mill 3 is connected to another air-coal burner 13 in the boiler 1;

[0052] The gas drying system 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 which may include several branches): one path is directly connected to the pulverized coal mill 3; one path is located upstream of the pulverized coal burner 13 connected to the pulverized coal mill 3; one path is connected to the subsequent hot medium pulverized coal delivery system; one path is connected to the main combustion pulverized coal mill 2; and the remaining path is located upstream of the pulverized coal burner 13 connected to the main combustion pulverized coal mill 2. The second drying gas unit 8 is also divided into five paths: one path is directly connected to the pulverized coal mill 3; one path is located upstream of the pulverized coal burner 13 connected to the pulverized coal mill 3; one path is connected to the hot medium pulverized coal delivery system; one path is connected to the main combustion pulverized coal mill 2; and the remaining path is located upstream of the pulverized coal burner 13 connected to the main combustion pulverized coal mill 2. The third drying gas unit 9 is divided into three paths: one path is connected to the main combustion coal mill 2, one path is connected to the pulverized coal storage mill 3, and the remaining path is connected to the hot medium conveying system. The first and second drying gases in the first and second drying gas units 7 and 8 respectively come from the boiler 1 and / or an adjacent boiler 1, and the first and second drying gases are the boiler hot primary air and cold primary air, respectively. The third drying gas in the third drying gas unit 9 comes from the 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 combustion coal mill 2 and the pulverized coal storage mill 3, and to transport the pulverized coal produced after grinding in the pulverized coal storage mill 3 to the downstream equipment (fine powder separator 4) and the air-coal burner 13, and to transport the pulverized coal produced after grinding in the main combustion coal mill 2 to the air-coal burner 13. The transportation process forms primary air-coal.

[0053] Fine powder separator 4 is located downstream of and connected to the pulverized coal mill 3, and is used to separate the primary air and pulverized coal conveyed from the pulverized coal mill 3 to form pulverized coal and exhaust gas (the connecting pipe between the pulverized coal mill 3 and the fine powder separator 4 can be led out from the equipment body of the pulverized coal mill 3).

[0054] Exhaust gas blower 5 is located downstream of and connected to the fine powder separator 4 to collect the exhaust gas generated in the fine powder separator 4. The outlet of the exhaust gas blower 5 is connected to the exhaust gas burner 11 in the boiler 1 and the pulverized coal mill 3, respectively.

[0055] A pulverized coal bin 6 is located downstream of and connected to the fine powder separator 4 to collect the pulverized coal generated in the fine powder separator 4.

[0056] A pulverized coal conveying system includes an impeller feeder 10 and a pulverized coal mixer 14. The impeller feeder 10 is located downstream of and connected to the pulverized coal silo 6, and the pulverized coal mixer 14 is located downstream of and connected to the impeller feeder 10. The impeller feeder 10 is used to convey pulverized coal from the pulverized coal silo 6 to the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is connected to the pulverized coal silo burner 12. A first drying gas unit 7, a second drying gas unit 8, and a third drying gas unit 9 are connected to the pulverized coal mixer 14. By mixing the first, second, and third drying gases from the first drying gas unit 7, the second drying gas unit 8, and the third drying gas unit 9 to form a heat medium, which is then introduced into the pulverized coal mixer 14, the pulverized coal to be conveyed to the pulverized coal silo burner 12 can be preheated (the pulverized coal in the pulverized coal silo 6 can be conveyed to the pulverized coal silo burner 12 through the combined action of the impeller feeder 10 and the first, second, and third drying gases).

[0057] Specifically, in Embodiment 1 above, the hot primary air (first drying gas) and cold primary air (second drying gas) from the boiler are mixed, and then mixed with the hot flue gas (third drying gas) from inside or outside the boiler. The resulting mixed heat medium is sent to the main combustion coal mill 2 and the pulverized coal storage mill 3 to dry and transport the coal being ground in the main combustion coal mill 2 and the pulverized coal storage mill 3. After grinding and drying, primary air-coal mixture is formed. The primary air-coal mixture formed in the pulverized coal storage mill 3 is discharged from the top and mixed with the hot and cold primary air from the boiler. It is then transported through a pipeline to the pulverized coal burner 13 of the boiler 1 for combustion, providing heat to the boiler. The primary air-coal mixture formed in the main combustion coal mill 2 is discharged from the top and mixed with the hot and cold primary air from the boiler. It is then transported through a pipeline to another pulverized coal burner 13 of the boiler 1 for combustion, providing heat to the boiler. When coal powder needs to be stored in the coal powder silo 6, the pulverizing pipeline valve above the coal storage mill 3 is opened (this pulverizing pipeline can be led out from the main body of the coal storage mill 3 or from the primary air-coal pulverizing pipeline at the outlet of the coal storage mill 3). The primary air-coal pulverizing gas formed in the coal storage mill 3 is transported to the fine powder separator 4 through the pulverizing pipeline for air-coal separation, forming coal powder and exhaust gas. The coal powder enters the coal powder silo 6 for storage, while the exhaust gas enters the exhaust gas blower 5. The exhaust gas separated from the fine powder separator 4 is divided into two paths by the exhaust gas blower 5. One path is sent to the exhaust gas burner 11 of the boiler 1 for combustion, providing heat to the boiler; the other path is sent through a pipeline to the inlet of the coal storage mill 3 to mix with the first, second, and third dry gases for recycling. These two paths can be used simultaneously or one path can be used alone. When the pulverized coal in the pulverized coal silo 6 needs to be used for combustion in the boiler 1, the pulverized coal in the pulverized coal silo 6 is conveyed to the pulverized coal mixer 14 through the impeller feeder 10. The hot primary air and cold primary air from the boiler are mixed, and then mixed with the hot flue gas inside or discharged from the boiler to form a heat medium. The heat medium is conveyed to the pulverized coal mixer 14 through the pipeline. After the heat medium and pulverized coal are mixed in the pulverized coal mixer 14, they enter the pulverized coal burner 12 of the boiler 1 through the pulverized coal delivery pipeline for combustion, providing heat to the boiler.

[0058] Because the primary air-coal concentration output by the main combustion coal mill 2 is low in the first 5-10 minutes of operation, the air-coal burner 13 connected to the main combustion coal mill 2 in boiler 1 may fail to ignite. However, the pulverized coal burner 12 set in Example 1 can compensate for the insufficient heat input caused by the failure of the air-coal burner 13 in boiler 1 to ignite, thus solving the problem of the air-coal burner 13 failing to ignite in the first 5-10 minutes of operation. This facilitates the rapid load change of the coal-fired power unit and improves the operational flexibility of the coal-fired power unit under complex coal quality conditions. It also solves the fuel supply problem. When the coal-fired power unit increases its load, the dual-source multi-combustion system designed in Example 1 can quickly increase the amount of fuel (pulverized coal) to the pulverized coal burner 12 (equivalent to the boiler) through the replenishment of the pulverized coal silo 6. This overcomes the disadvantage of the lag in fuel addition in the existing boiler pulverizing system. Therefore, after the coal-fired power unit receives the fuel addition command, the boiler can immediately generate air-coal that meets the combustion concentration requirements, greatly improving the operational flexibility of the coal-fired power unit and increasing the rapid load change rate of the unit.

[0059] Example 2

[0060] like Figure 3 As shown in the figure, this embodiment 2 designs a dual-source multi-fuel system, which includes the following structural configuration:

[0061] Boiler 1, which is equipped with one exhaust gas burner 11, two pulverized coal burners 12 and three air-coal burners 13;

[0062] A main combustion coal mill 2 is used to grind coal to produce pulverized coal, and the main combustion coal mill 2 is connected to a pulverized coal burner 13 in the boiler 1;

[0063] Two pulverized coal mills 3 are used to grind coal to produce pulverized coal. The two pulverized coal mills 3 are respectively connected to two other air-coal burners 13 in the boiler 1.

[0064] The gas drying system 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 which may include several branches). One path is connected to two pulverized coal mills 3, another path is located upstream of two air-coal burners 13 connected to the two pulverized coal mills 3, another path is connected to the subsequent hot medium pulverized coal feeding system, and another path is connected to the main combustion coal mill 2. The remaining path is located upstream of the air-coal burner 13 connected to the main combustion coal mill 2. Similarly, the second drying gas unit 8 is also divided into five paths. One path is connected to two pulverized coal mills 3, another path is located upstream of two air-coal burners 13 connected to the two pulverized coal mills 3, another path is connected to the hot medium pulverized coal feeding system, another path is connected to the main combustion coal mill 2, and the remaining path is located upstream of the air-coal burner 13 connected to the main combustion coal mill 2. Upstream of 3; the third drying gas unit 9 is divided into three paths: one path is connected to the main combustion coal mill 2, one path is connected to two pulverized coal mills 3 respectively, and the remaining path is connected to the hot medium conveying system; the first and second drying gases in the first and second drying gas units 7 and 8 respectively come from the boiler 1 and / or the adjacent boiler 1, and the first and second drying gases are the boiler hot primary air and cold primary air respectively; the third drying gas in the third drying gas unit 9 comes from the 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; the gas drying system is used to dry the coal being ground in the main combustion coal mill 2 and the pulverized coal mill 3, and to transport the coal powder produced after grinding in the two pulverized coal mills 3 to the downstream equipment (fine powder separator 4) and the two air-coal burners 13 respectively, and to transport the coal powder produced after grinding in the main combustion coal mill 2 to the air-coal burners 13, and the conveying process forms primary air-coal;

[0065] Fine powder separator 4 is located downstream of and connected to the pulverized coal mill 3 (two pulverized coal mills 3 share one fine powder separator 4). The fine powder separator 4 is used to separate the primary air and pulverized coal conveyed from the pulverized coal mill 3 to form pulverized coal and exhaust gas (the connecting pipe between the pulverized coal mill 3 and the fine powder separator 4 can be led out from the equipment body of the pulverized coal mill 3).

[0066] Exhaust gas blower 5 is located downstream of and connected to the fine powder separator 4 to collect the exhaust gas generated in the fine powder separator 4. The outlet of the exhaust gas blower 5 is connected to the exhaust gas burner 11 and the two pulverized coal mills 3 in the boiler 1, respectively.

[0067] A pulverized coal bin 6 is located downstream of and connected to the fine powder separator 4 to collect the pulverized coal generated in the fine powder separator 4.

[0068] A pulverized coal conveying system includes an impeller feeder 10 and a pulverized coal mixer 14. The impeller feeder 10 is located downstream of and connected to the pulverized coal bin 6, and the pulverized coal mixer 14 is located downstream of and connected to the impeller feeder 10. The impeller feeder 10 is used to convey pulverized coal from the pulverized coal bin 6 to the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is connected to two pulverized coal bin burners 12. A first drying gas unit 7, a second drying gas unit 8, and a third drying gas unit 9 are connected to the pulverized coal mixer 14. By mixing the first, second, and third drying gases from 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 pulverized coal bin burners 12 can be preheated (the pulverized coal in the pulverized coal bin 6 can be conveyed to the pulverized coal bin burners 12 through the combined action of the impeller feeder 10 and the first, second, and third drying gases).

[0069] Specifically, the difference between Embodiment 2 and Embodiment 1 lies in the number of pulverized coal mills 3, pulverized coal silo burners 12, and air-pulverized coal burners 13 in Embodiment 2, although the principle remains the same. In Embodiment 2, the two pulverized coal mills 3 can be used simultaneously or individually. The air-pulverized coal burners 13 corresponding to the pulverized coal mills 3 are used simultaneously or individually depending on the usage of the pulverized coal mills 3. In Embodiment 2, two pulverized coal silo burners 12 can be used simultaneously, or only one can operate.

[0070] Example 3

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

[0072] Boiler 1, which is equipped with two exhaust gas burners 11, one pulverized coal burner 12 and three air-coal burners 13;

[0073] A main combustion coal mill 2 is used to grind coal to produce pulverized coal, and the main combustion coal mill 2 is connected to a pulverized coal burner 13 in the boiler 1;

[0074] Two pulverized coal mills 3 are used to grind coal to produce pulverized coal. The two pulverized coal mills 3 are respectively connected to two other air-coal burners 13 in the boiler 1.

[0075] The gas drying system 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 which may include several branches). One path is connected to two pulverized coal mills 3, another path is located upstream of two air-coal burners 13 connected to the two pulverized coal mills 3, another path is connected to the subsequent hot medium pulverized coal feeding system, and another path is connected to the main combustion coal mill 2. The remaining path is located upstream of the air-coal burner 13 connected to the main combustion coal mill 2. Similarly, the second drying gas unit 8 is also divided into five paths. One path is connected to two pulverized coal mills 3, another path is located upstream of two air-coal burners 13 connected to the two pulverized coal mills 3, another path is connected to the hot medium pulverized coal feeding system, and another path is connected to the main combustion coal mill 2. The remaining path is located upstream of the air-coal burner 13 connected to the main combustion coal mill 2. Upstream of the device 13; the third drying gas unit 9 is divided into three paths: one path is connected to the main combustion coal mill 2, one path is connected to two pulverized coal mills 3 respectively, and the remaining path is connected to the hot medium conveying system; the first and second drying gases in the first and second drying gas units 7 and 8 respectively come from the boiler 1 and / or the adjacent boiler 1, and the first and second drying gases are the boiler hot primary air and cold primary air respectively; the third drying gas in the third drying gas unit 9 comes from the 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; the gas drying system is used to dry the coal being ground in the main combustion coal mill 2 and the pulverized coal mill 3, and to transport the coal powder produced after grinding in the two pulverized coal mills 3 to the two fine powder separators 4 and the two air-coal burners 13 respectively, and to transport the coal powder produced after grinding in the main combustion coal mill 2 to the air-coal burners 13, and the conveying process forms primary air-coal;

[0076] Two fine powder separators 4 are respectively located downstream of and connected to two pulverized coal mills 3. The two pulverized coal 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 and pulverized coal conveyed from the two pulverized coal mills 3 to form pulverized coal and exhaust gas (the connecting pipe between the pulverized coal mill 3 and the fine powder separator 4 can be led out from the equipment body of the pulverized coal mill 3).

[0077] Exhaust gas fan 5 is located downstream of and connected to two fine powder separators 4 (two fine powder separators 4 share one exhaust gas fan 5) to collect the exhaust gas generated in the fine powder separators 4. The outlet of the exhaust gas fan 5 is connected to two exhaust gas burners 11 and two coal storage mills 3 in the boiler 1.

[0078] A pulverized coal bin 6 is located downstream of and connected to the fine powder separator 4 to collect the pulverized coal generated in the fine powder separator 4.

[0079] A pulverized coal conveying system includes an impeller feeder 10 and a pulverized coal mixer 14. The impeller feeder 10 is located downstream of and connected to the pulverized coal silo 6, and the pulverized coal mixer 14 is located downstream of and connected to the impeller feeder 10. The impeller feeder 10 is used to convey pulverized coal from the pulverized coal silo 6 to the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is connected to the pulverized coal silo burner 12. A first drying gas unit 7, a second drying gas unit 8, and a third drying gas unit 9 are connected to the pulverized coal mixer 14. By mixing the first, second, and third drying gases from 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 pulverized coal silo burner 12 can be preheated (the pulverized coal in the pulverized coal silo 6 can be conveyed to the pulverized coal silo burner 12 through the combined action of the impeller feeder 10 and the first, second, and third drying gases).

[0080] Example 4

[0081] like Figure 5 As shown, this embodiment 4 designs a dual-source multi-fuel system, which includes the following structural configuration:

[0082] Boiler 1, which is equipped with one exhaust gas burner 11, one pulverized coal burner 12 and two air-coal burners 13;

[0083] A main combustion coal mill 2 is used to grind coal to produce pulverized coal, and the main combustion coal mill 2 is connected to a pulverized coal burner 13 in the boiler 1;

[0084] A pulverized coal mill 3 is used to grind coal to produce pulverized coal, and the pulverized coal mill 3 is connected to another air-coal burner 13 in the boiler 1;

[0085] The gas drying system 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 (each of which may include several branches). One path is directly connected to the pulverized coal storage mill 3, one path is connected to the subsequent hot medium pulverized coal conveying system, and the remaining 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 mill 3, one path is connected to the hot medium pulverized coal conveying system, and the remaining path is connected to the main combustion pulverized coal mill 2. The first and second... The first and second drying gases in drying gas units 7 and 8 are respectively from this boiler 1 and / or an adjacent boiler 1. The first and second drying gases are respectively the boiler hot primary air and cold primary air. The gas drying system is used to dry the coal being ground in the main combustion coal mill 2 and the pulverized coal mill 3, and to transport the pulverized coal produced after grinding in the pulverized coal mill 3 to the downstream equipment (fine powder separator 4) and the air-coal burner 13, and to transport the pulverized coal produced after grinding in the main combustion coal mill 2 to the air-coal burner 13. The transport process forms primary air-coal.

[0086] A fine powder separator 4 is located downstream of and connected to the pulverized coal mill 3, and is used to separate the primary air and pulverized coal conveyed from the pulverized coal mill 3 to form pulverized coal and exhaust gas.

[0087] Exhaust gas blower 5 is located downstream of and connected to the fine powder separator 4 to collect the exhaust gas generated in the fine powder separator 4. The outlet of the exhaust gas blower 5 is connected to the exhaust gas burner 11 in the boiler 1 and the pulverized coal mill 3, respectively.

[0088] A pulverized coal bin 6 is located downstream of and connected to the fine powder separator 4 to collect the pulverized coal generated in the fine powder separator 4.

[0089] A pulverized coal conveying system includes an impeller feeder 10 and a pulverized coal mixer 14. The impeller feeder 10 is located downstream of and connected to the pulverized coal silo 6, and the pulverized coal mixer 14 is located downstream of and connected to the impeller feeder 10. The impeller feeder 10 is used to convey pulverized coal from the pulverized coal silo 6 to the pulverized coal mixer 14. The outlet of the pulverized coal mixer 14 is connected to the pulverized coal silo burner 12. A first drying gas unit 7 and a second drying gas unit 8 are connected to the pulverized coal mixer 14. By mixing the first and second drying gases from the first drying gas unit 7 and the second drying gas unit 8 and introducing them into the pulverized coal mixer 14, the pulverized coal to be conveyed to the pulverized coal silo burner 12 can be preheated (the pulverized coal in the pulverized coal silo 6 can be conveyed to the pulverized coal silo burner 12 through the combined action of the impeller feeder 10 and the first and second drying gases).

[0090] The difference between the dual-source multi-fuel system designed in Embodiment 4 and Embodiment 1 is that the gas drying system in Embodiment 4 does not have a third drying gas unit 9, and the first and second drying gas units 7 and 8 in Embodiment 4 are set in three separate paths, which is different from the five-path setting in Embodiment 1. The rest is the same as in Embodiment 1.

[0091] For coal types with low volatile matter content, flue gas (third drying gas) can be omitted as the drying gas; only the boiler's hot primary air (first drying gas) and cold primary air (second drying gas) can be used. Therefore, the dual-source multi-combustion system in Example 4 does not include a third drying gas 9. Furthermore, since the system in Example 4 lacks a third drying gas (flue gas) for drying and conveying the coal in the main combustion coal mill 2 and the pulverized coal storage mill 3, the amount of the first and second drying gases introduced into the main combustion coal mill 2 and the pulverized coal storage mill 3 can be increased (i.e., Example 4 changes the five-way configuration of the first and second drying gas units 7 and 8 in Example 1 to a three-way configuration). This not only benefits the drying of the coal in the mill and the conveying of the ground coal powder, but also avoids wear and tear on the equipment caused by the third drying gas, thus preventing a reduction in equipment lifespan and ensuring reliable equipment operation, as the third drying gas is not introduced into the main combustion coal mill 2 and the pulverized coal storage mill 3.

[0092] The above-described preferred embodiments of this utility model are for illustrative purposes only and are not intended to limit the scope of this utility model. Any obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.

Claims

1. A dual-source, multi-fuel system, characterized in that, The dual-source, multi-fuel system includes the following structural configuration: Boiler (1), wherein at least one exhaust gas burner (11), at least one pulverized coal burner (12) and at least two air-coal burners (13); A number of main combustion coal mills (2) are used to grind coal to produce pulverized coal, and the main combustion coal mills (2) are connected in communication with one or more air-coal burners (13) in the boiler (1); A plurality of pulverized coal mills (3) are used for pulverizing coal to produce pulverized coal, and the plurality of pulverized coal mills (3) are respectively connected to the remaining air-coal burners (13) in the boiler (1); A gas drying system is connected to the main combustion coal mill (2) and the pulverized coal mill (3) respectively. The gas drying system is used to dry the coal ground in the main combustion coal mill (2) and the pulverized coal mill (3), and to transport the coal powder generated after grinding to the downstream equipment and the air-coal burner (13). The transport process forms a primary air-coal burner. Several fine powder separators (4) are located downstream of and connected to the pulverized coal mill (3) to separate the primary air powder conveyed from the pulverized coal mill (3) to form pulverized coal and exhaust gas. Several exhaust gas blowers (5) are located downstream of and connected to the fine powder separator (4) for collecting exhaust gas generated in the fine powder separator (4). The outlets of the exhaust gas blowers (5) are respectively connected to the exhaust gas burner (11) in the boiler (1) and the coal storage mill (3). Several coal powder bins (6) are located downstream of and connected to the fine powder separator (4) for collecting coal powder generated in the fine powder separator (4); A heat medium conveying system is located downstream of and connected to the pulverized coal silo (6) for conveying pulverized coal in the pulverized coal silo (6) to the pulverized coal burner (12). The gas drying system is also connected to the heat medium conveying system for preheating the pulverized coal conveyed to the pulverized coal burner (12).

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

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

4. The dual-source multi-fuel system according to claim 1, characterized in that, The gas drying system includes: a first drying gas unit (7) and a second drying gas unit (8); the gas drying system may or may not include a third drying gas unit (9); The first drying gas unit (7) is connected to several main combustion coal mills (2), several coal storage mills (3) and a heat medium powder delivery system respectively. The second drying gas unit (8) is connected to several main combustion coal mills (2), several coal storage mills (3) and a hot medium coal conveying system respectively; The third drying gas unit (9) is connected to several main combustion coal mills (2), several coal storage mills (3), and a hot medium coal conveying system.

5. A dual-source multi-fuel system according to claim 4, characterized in that, The first dry gas unit (7) is divided into five paths, one of which is directly connected to several pulverized coal mills (3), one is located upstream of the air-coal burner (13) connected to the pulverized coal mill (3), one is connected to the heat medium pulverized coal delivery system, one is connected to several main combustion pulverized coal mills (2), and the remaining path is located upstream of the air-coal burner (13) connected to the main combustion pulverized coal mill (2). The second drying gas unit (8) is divided into five paths. One path is directly connected to several pulverized coal mills (3), another path is located upstream of the air-coal burner (13) connected to the pulverized coal mills (3), another path is connected to the heat medium pulverized coal delivery system, another path is connected to several main combustion pulverized coal mills (2), and the remaining path is located upstream of the air-coal burner (13) connected to the main combustion pulverized coal mills (2).

6. A dual-source multi-fuel system according to claim 4 or 5, characterized in that, The first dry gas in the first dry gas unit (7) comes from the boiler (1) and / or the adjacent boiler (1), and the first dry gas is the boiler hot primary air; The second dry gas in the second dry gas unit (8) comes from this boiler (1) and / or an adjacent boiler (1), and the second dry gas is boiler cold primary air; The third dry gas in the third dry gas unit (9) comes from the boiler (1) and / or the adjacent boiler (1), and the third dry 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, The gas drying system may or may not include a third drying gas unit (9) depending on the volatile matter content of the coal ground in the main combustion coal mill (2) and the pulverized coal mill (3); for coal with low volatile matter content, the third drying gas unit (9) is not set up, and vice versa.

8. A dual-source multi-fuel system according to claim 1, characterized in that, The hot medium pulverized coal feeding system includes: several impeller feeders (10) and several pulverized coal mixers (14); The impeller feeder (10) is located downstream of and connected to the pulverized coal bin (6), and the pulverized coal mixer (14) is located downstream of and connected to the impeller feeder (10). The impeller feeder (10) is used to transport pulverized coal in the pulverized coal bin (6) to the pulverized coal mixer (14). The outlet of the pulverized coal mixer (14) is connected to the pulverized coal 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 pulverized coal 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 mill (2) and the pulverized coal mill (3) are respectively selected as medium-speed coal mills or double-inlet double-outlet ball mills.

Images