Optimization control system for reducing power consumption rate of primary fan of coal-fired power plant

Abstract

The invention discloses an optimal control system for reducing the power consumption rate of a primary fan of a coal-fired power plant, which comprises a coal mill, a hot primary air input end, a cold primary air input end, two pulverized coal separators, two coal feeding driving devices and two pulverized coal separators, and primary air fans at the hot primary air input end and the cold primary air input end are adjusted by introducing DCS primary air fan load control logic through a primary air pressure boiler load control model. Aiming at conventional coal types, main steam flow and primary air pressure boiler load control characteristics, a primary air pressure boiler load control curve is fitted, DCS primary air fan load control logic is introduced, primary air fan output rough adjustment is carried out according to the primary air pressure boiler load control curve, and primary air fan output rough adjustment is carried out according to the primary air pressure boiler load control curve. The purpose of reducing the throttling loss of the capacity air baffle of the coal mill as much as possible is achieved, the fluctuation amplitude of combustion parameters in the boiler load rising and falling process is reduced, and the boiler operation safety is improved.

Description

Technical Field

[0001] The invention relates to the technical field of equipment control of coal-fired power plants, and in particular to an optimization control system for reducing the power consumption rate of a primary fan of a coal-fired power plant. Background Art

[0002] The primary fan is a device that provides drying and conveying air for the pulverizing system in a coal-fired thermal power plant. The air is pressurized by the primary fan and divided into two paths. One path is converted into hot primary air at about 330°C through the air preheater for heat exchange with the high-temperature flue gas and enters the hot primary air main pipe; the other path is cold air that enters the cold primary air main pipe. The coal mill is a device that grinds coal powder for the boiler of a coal-fired power plant. The cold and hot primary air main pipes are branched out to the coal mill inlet, providing the coal mill with an air source for drying and conveying coal powder.

[0003] A primary air main isolation door is installed at the inlet of the double-inlet and double-outlet ball mill, and a hot primary air adjustment door and a cold primary air adjustment door are installed in front of the main isolation door. The hot air adjustment door adjusts the air volume of the mill, and the cold primary air adjustment door adjusts the outlet temperature of the mill. Capacity air and bypass air adjustment doors are installed on both sides. The capacity air door is used to carry coal powder and adjust the coal mill load, and the bypass air is used to pre-dry the raw coal and transport coal powder.

[0004] At present, the load of the coal mill, that is, the amount of coal ground by the coal mill, is adjusted by adjusting the opening of the capacity wind dampers on both sides of the coal mill. Since the opening of the capacity wind dampers of the coal mill is often maintained below 45%, the capacity wind opening is controlled too small, resulting in large primary air throttling losses. In order to maintain the capacity air volume of the coal mill, the primary air pressure of the primary fan must be increased, which will directly lead to an increase in the power consumption rate of the primary fan, thereby increasing the coal consumption of the unit. At the same time, because the bypass wind damper is manually operated and there is no effective adjustment basis, the primary air volume in some load sections is too large, and the primary air volume in low or high load sections is relatively low, there is a risk of powder accumulation and blockage in the powder pipe. Summary of the invention

[0005] The object of the present invention is to provide an optimization control system for reducing the power consumption rate of a primary fan in a coal-fired power plant.

[0006] According to one aspect of the present disclosure, the following technical solution is provided: an optimization control system for reducing the power consumption rate of a primary air fan in a coal-fired power plant, the system comprising a coal mill, a hot primary air input end, a cold primary air input end and two coal powder separators, and also comprising two coal inlet drive devices and a coal powder separator, the coal inlets at both ends of the coal mill are connected to pipeline 2 and pipeline 3, a capacity damper is installed on pipeline 2, a bypass damper is installed on pipeline 3, the pipeline 2 and one end of the pipeline are connected to pipeline 1, and the two pipelines 1 are connected to the hot primary air input end and the cold primary air input end, respectively. The two pulverized coal separators are connected to the coal outlets at both ends of the coal mill. The primary fans at the hot primary air input end and the cold primary air input end are regulated by introducing the DCS primary fan load control logic through the primary air pressure boiler load control model. According to the single-side air volume control curve of the coal mill, the air volume on both sides of the coal mill is controlled by adjusting the bypass adjustment baffles on both sides of the coal mill.

[0007] According to at least one embodiment of the present disclosure, an optimized control system for reducing the power consumption rate of a primary fan in a coal-fired power plant is disclosed, wherein a sealed air system is installed on the coal mill, and the sealed air system is used to prevent leakage of coal powder and hot air from the coal mill.

[0008] According to the optimized control system for reducing the power consumption rate of primary fans in coal-fired power plants according to at least one embodiment of the present disclosure, the primary air pressure boiler load control model includes a primary air pressure optimization control curve.

[0009] According to the optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants of at least one embodiment of the present disclosure, the wind volume measuring device is a wind speed sensor.

[0010] According to the optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to at least one embodiment of the present disclosure, the coal mill single-side air volume control model includes a single-side air volume load control curve.

[0011] According to at least one embodiment of the present disclosure, an optimized control system for reducing the power consumption rate of primary fans in coal-fired power plants, when the average opening of the capacity wind damper of the capacity damper reaches 65%, the current primary wind pressure control curve is increased by 0.3 kPa each time as a dynamic optimization step until the average opening of the capacity wind damper of the capacity damper reaches 55%. The dynamic optimization adjustment is completed, and then the primary wind pressure optimization control curve is fitted to replace the original control curve.

[0012] According to at least one embodiment of the present disclosure, an optimized control system for reducing the power consumption rate of primary fans in coal-fired power plants, when the average opening of the capacity wind damper of the capacity damper reaches 45%, the current primary wind pressure control curve is reduced by 0.3 kPa each time as a dynamic optimization step until the average opening of the capacity wind damper of the capacity damper reaches 55%. The dynamic optimization adjustment is completed, and then the primary wind pressure optimization control curve is fitted to replace the original control curve.

[0013] According to at least one embodiment of the present disclosure, an optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants is disclosed. The primary fan load control logic is implemented by sending a unit load instruction to a load controller of the primary fan. The load control of the primary fan adjusts the speed of the motor inverter of the corresponding primary fan through a primary wind pressure optimization control curve. The air volume on one side of the coal mill is controlled according to the load curve of the coal mill by measuring the air volume on both sides of the coal mill using a grid method. Technical effects and advantages of the present invention: The present invention aims at the clogging characteristics of the powder tube of the coal mill, the wind speed control characteristics and the single-side air volume control load curve of the coal mill design, then determines the single-side air volume control curve of the coal mill, introduces the DCS coal mill single-side air volume control logic and the DCS coal mill bypass wind damper control logic, and performs a rough adjustment of the primary fan output according to the primary wind pressure boiler load control curve, so as to reduce the throttling loss of the coal mill capacity wind damper as much as possible. This coal mill load adjustment method can improve the load response characteristics of the coal mill, is beneficial to reducing the fluctuation amplitude of the combustion parameters in the process of boiler load increase and decrease, and is beneficial to improving the safety of boiler operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0015] Figure 1 It is a structural diagram of an optimization control system for reducing the power consumption rate of a primary fan in a coal-fired power plant according to the present invention.

[0016] Figure 2 This is the load characteristic diagram of primary wind pressure optimization control of the present invention.

[0017] Figure 3 This is a primary wind pressure optimization control curve diagram of the present invention.

[0018] Figure 4 It is a flow chart of a method for dynamic optimization of primary wind pressure in an embodiment of the present invention.

[0019] Figure 5 It is a flow chart of a method for dynamic optimization of primary wind pressure in another embodiment of the present invention.

[0020] Figure 6 It is a curve diagram showing the relationship between the capacity air volume, bypass air volume and the output of the coal mill of the present invention.

[0021] The specific reference numerals in the figure are: Coal mill; 2. Coal feed drive device; 3. Feed valve; 4. Hot primary air input; 5. Cold primary air input; 6. Air volume measuring device; 7. Capacity damper; 8. Bypass damper; 9. Coal powder separator; 10. Sealed air system; 11. Pipeline one; 12. Pipeline two; 13. Pipeline three. DETAILED DESCRIPTION

[0022] For descriptive purposes, the present disclosure may use spatially relative terms such as "below," "beneath," "below," "above," "on," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, a component described as "below" or "beneath" another component or feature would then be positioned "above" the other component or feature. Thus, the exemplary term "below" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and as such, the spatially relative descriptors used herein should be interpreted accordingly.

[0023] like Figure 1 As shown, the present disclosure discloses an optimization control system for reducing the power consumption rate of a primary air fan in a coal-fired power plant, the system comprising a coal mill 1, a hot primary air input terminal 4, a cold primary air input terminal 5 and two coal powder separators 9, and also comprising two coal feeding drive devices 2 and coal powder separators 9; The coal inlets at both ends of the coal mill 1 are connected to the pipeline 2 12 and the pipeline 3 13. The pipeline 2 12 is installed with a capacity damper 7, and the pipeline 3 13 is installed with a bypass damper 8. One end of the pipeline 2 12 and the pipeline 13 are connected to the pipeline 1 11. The two pipelines 11 are connected to the hot primary air input end 4 and the cold primary air input end 5 respectively, and the pipeline 1 11 and both sides of the coal mill 1 are installed with an air volume measuring device 6. One end of the pipeline 3 13 is connected to the coal feeding drive device 2, and the coal feeding drive device 2 is connected to the coal inlet of the coal mill 1 through the feed valve 3. The coal feeding drive device 2 is used to transfer the burning coal in the coal bunker. The coal is fed into the cylinder of the coal mill 1 through the auger, and the two coal powder separators 9 are connected to the coal outlets at both ends of the coal mill 1. Dry coal and hot air with a certain temperature carrying coal powder, i.e., the volumetric air at both ends of the coal mill 1, enter the two ends of the coal mill 1. The volumetric air volume is adjusted by the volumetric air dampers at both ends. The temperature of the volumetric air entering the coal mill 1 is adjusted by the total hot primary air damper and the cold primary air damper of the coal mill 1. The hot primary air comes from the air preheater outlet, and the cold primary air comes from the primary air fan outlet mother pipe. The primary air fans at the hot primary air input end 4 and the cold primary air input end 5 are adjusted by introducing the DCS primary air fan load control logic through the primary air pressure boiler load control model; The bypass air volume at both ends of the coal mill 1 is adjusted by the baffles of the bypass dampers 8 at both ends. The purpose is to supplement the air volume according to the change of the volumetric air volume to ensure that the coal powder pipeline at the outlet of the coal powder separator 9 maintains a certain wind speed without blocking the pipe. The volumetric air volume of the coal mill 1 is proportional to the load of the coal mill 1. Figure 6 As shown, when the load of coal mill 1 is high, the capacity air volume is large, and when the load of coal mill 1 is low, the capacity air volume is small.

[0024] In this embodiment, a sealing air system 10 is installed on the coal mill 1. The sealing air system forms a positive pressure area at a key position of the equipment by injecting a sealing air, thereby preventing the leakage of coal powder and hot air from the coal mill 1.

[0025] In this embodiment, the air volume measuring device 6 is a wind speed sensor.

[0026] In this embodiment, the primary air pressure boiler load control model includes a primary air pressure optimization control curve.

[0027] In this embodiment, the coal mill single-side air volume control model includes a coal mill single-side air volume control curve.

[0028] The method for determining the above primary wind pressure optimization control curve is as follows: Through the test of 9 working conditions of main steam flow rate of 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100% respectively in the power plant using conventional coal, the control principle of the capacity damper opening of the double-inlet and double-outlet ball mill is maintained at 55%, and the control characteristics of main steam flow rate and primary air pressure boiler load for conventional coal are determined (see Figure 2 ), and then fit it into a wind pressure boiler load control curve (see Figure 3 ), the DCS primary fan load control logic is introduced, and the primary fan output is roughly adjusted according to the primary wind pressure boiler load control curve, so as to minimize the throttling loss of the coal mill capacity wind damper. That is, the adjustment of the unit load is first the adjustment of the primary fan output and the primary wind pressure; followed by the fine adjustment of the coal mill capacity wind damper. This coal mill load adjustment method will improve the coal mill load response characteristics, which is beneficial to reducing the fluctuation amplitude of combustion parameters during the boiler load increase and decrease process, and is beneficial to improving the safety, environmental protection and economy of boiler operation.

[0029] The method for determining the above-mentioned coal mill one-side air volume optimization control curve is as follows: according to the coal mill one-side air volume control curve provided by the coal mill manufacturer, the coal mill one-side air volume control test is carried out at 10%, 30%, 50%, 70%, 90% and 100% load of the coal mill to determine the minimum air volume at which the powder tube of the coal mill is not blocked under the test working condition of the coal mill, and then the coal mill one-side air volume control curve is fitted to replace the original manufacturer's design control curve.

[0030] The present invention takes a 330MW coal-fired power unit equipped with three double-inlet and double-outlet steel ball coal mills as an object to illustrate the method for determining a wind pressure optimization control curve. Four powder pipes are arranged at the drive end and non-drive end outlets of each coal mill respectively.

[0031] 20-30% load operation of one coal mill B, that is, use 2 capacity wind dampers of coal mill B1 and B2 to adjust the unit load; 30-80% load operation of coal mills A and B, that is, use 4 capacity wind dampers of coal mill A1 and A2 and coal mill B1 and B2 to adjust the unit load; 80-100% load operation of three coal mills A, B, and C, that is, use 6 capacity wind dampers of coal mill A1 and A2, coal mill B1 and B2, and coal mill C1 and C2 to adjust the unit load. Specific data of the 9 test conditions are detailed in Figure 2 The appropriate primary air pressure was determined by maintaining the wind damper opening of the operating coal mill capacity corresponding to the 9 test conditions at 55%.

[0032] As the performance of the coal mill deteriorates, including coal mill liner wear, reduced steel ball loading, and imbalanced steel ball ratio, the coal mill output decreases. In order to take on the load, the primary air volume is forced to increase, which will cause the coal mill capacity wind damper opening to exceed 65% on average, exceeding the capacity wind damper adjustment linear zone, making it impossible to increase the primary air volume of the coal mill, indicating that the primary air pressure control is currently low and the primary air pressure control curve needs to be dynamically corrected.

[0033] On the contrary, as the performance of the coal mill is improved, including increasing the coal mill steel ball loading, replacing the liner, screening the steel balls and optimizing the ratio, the coal mill grinding capacity is improved, resulting in an unreasonable primary air pressure control curve determined under the test conditions, making the coal mill capacity wind damper opening averagely less than 45%, the primary air system throttling loss is large, and the primary air pressure control curve needs to be dynamically corrected.

[0034] As the quality of coal entering the furnace deteriorates, including reduced calorific value and reduced volatile matter that cause lower boiler efficiency, the coal mill's load-bearing capacity decreases. In order to connect the load, the primary air volume is forced to increase, which will cause the coal mill's capacity wind damper opening to exceed 65% on average, exceeding the capacity wind damper adjustment linear zone, making it impossible to increase the coal mill's primary air volume. This indicates that the primary air pressure control is too low, and the primary air pressure control curve needs to be dynamically corrected.

[0035] On the contrary, as the quality of the coal entering the furnace improves, including the increase in calorific value and the increase in volatile matter that causes the boiler efficiency to increase, the load-carrying capacity of the pulverizer increases, resulting in an unreasonable primary air pressure control curve determined under the test conditions, making the average opening of the pulverizer capacity wind damper less than 45%, and the throttling loss of the primary air system large, and the primary air pressure control curve needs to be dynamically corrected.

[0036] like Figure 4 As shown, in this embodiment, if the performance of the coal mill deteriorates or the quality of the coal entering the furnace deteriorates, resulting in the average opening of the capacity wind damper of the capacity damper 7 reaching 65%, the current primary wind pressure control curve will be increased by 0.3 kPa each time as the dynamic optimization step until the average opening of the capacity wind damper of the capacity damper 7 reaches 55%. The dynamic optimization adjustment is completed, and then the primary wind pressure optimization control curve is fitted to replace the original control curve. This process is repeated to achieve dynamic optimization adjustment of the primary wind pressure.

[0037] like Figure 5 As shown, in this embodiment, the performance of the coal mill is improved or the quality of the coal entering the furnace is improved, resulting in the average opening of the capacity wind damper of the capacity damper 7 reaching 45%. In this case, the current primary wind pressure control curve is reduced by 0.3 kPa each time as the dynamic optimization step size, until the average opening of the capacity wind damper of the capacity damper 7 reaches 55%. The dynamic optimization adjustment is completed, and then the primary wind pressure optimization control curve is fitted to replace the original control curve. This process is repeated to achieve dynamic optimization adjustment of the primary wind pressure.

[0038] In this embodiment, the primary fan load control logic is to send the unit load command to the load controller of the primary fan. The load control of the primary fan adjusts the motor inverter speed of the corresponding primary fan through the primary wind pressure optimization control curve. The air volume device on both sides of the coal mill is measured by the installed grid method to control the single-side air volume of the coal mill according to the single-side air volume optimization curve of the coal mill.

[0039] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0041] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. An optimization control system for reducing the power consumption rate of a primary air fan in a coal-fired power plant, the system comprising a coal mill, a hot primary air input end, a cold primary air input end and two coal powder separators, characterized in that: It also includes two coal feeding drive devices and a coal powder separator. The coal inlets at both ends of the coal mill are connected to pipeline 2 and pipeline 3. A capacity damper is installed on pipeline 2, and a bypass damper is installed on pipeline 3. Pipe 2 and one end of pipeline are connected to pipeline 1. The two pipelines 1 are connected to the hot primary air input end and the cold primary air input end respectively, and air volume measuring devices are installed on pipeline 1 and both sides of the coal mill. One end of pipeline 3 is connected to the coal feeding drive device, and the coal feeding drive device is connected to the coal inlet of the coal mill through a feed valve. The two coal powder separators are connected to the coal outlets at both ends of the coal mill. The primary fans at the hot primary air input end and the cold primary air input end are adjusted by introducing the DCS primary fan load control logic through the primary air pressure boiler load control model, and the air volume on both sides of the coal mill is controlled by adjusting the adjustment baffles of the bypass dampers on both sides of the coal mill according to the single-side air volume control curve of the coal mill.

2. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 1 is characterized in that: The coal mill is equipped with a sealing air system, which is used to prevent leakage of coal powder and hot air from the coal mill.

3. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 1 is characterized in that: The primary air pressure boiler load control model includes a primary air pressure optimization control curve and a coal mill single-side air volume control curve.

4. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 1 is characterized in that: The wind volume measuring device is a wind speed sensor.

5. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 3 is characterized in that: When the average opening of the capacity damper of the capacity damper reaches 65%, the current wind pressure control curve is increased by 0.3 kPa each time as the dynamic optimization step, until the average opening of the capacity damper of the capacity damper 7 reaches 55%. The dynamic optimization adjustment is completed, and then the wind pressure optimization control curve is fitted to replace the original control curve.

6. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 3 is characterized in that: When the average opening of the capacity damper of the capacity damper reaches 45%, the current wind pressure control curve is reduced by 0.3 kPa each time as the dynamic optimization step, until the average opening of the capacity damper of the capacity damper 7 reaches 55%. The dynamic optimization adjustment is completed, and then the wind pressure optimization control curve is fitted to replace the original control curve.

7. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 3 is characterized in that: The primary fan load control logic is to send a unit load instruction to a load controller of the primary fan, and the load control of the primary fan adjusts the motor inverter speed of the corresponding primary fan through a primary wind pressure optimization control curve.

8. The optimization control system for reducing the power consumption rate of primary fans in coal-fired power plants according to claim 3 is characterized in that: The bypass damper of the coal mill adjusts the air volume on one side of the coal mill according to the coal feed amount on one side of the coal mill and the load control curve.

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