Primary air speed regulating method

Abstract

The application discloses a primary air speed adjusting method, which comprises the following steps: measuring the primary air speed corresponding to the burners of the same layer, calculating the air speed deviation percentage; repeating the calculation step, measuring and calculating the primary air speed corresponding to the burners of each layer, and calculating the deviation; arranging the deviation of each layer according to a table; adjusting the primary air speed corresponding to the burners of each layer layer by layer; adjusting the primary air speed by area according to the different position areas of the primary air speed in the furnace; and determining the symmetrical area according to the physical position of the burners, and checking the deviation of the symmetrical area. The primary air speed deviation is adjusted to a reasonable level through the air speed deviation percentage calculation and adjustment, the effect of the primary air speed adjustment is greatly improved, the uniformity of the thermal load of the boiler furnace is obviously improved, the steam parameters of the left and right sides of the boiler outlet are consistent, and the thermal deviation of the boiler is reduced.

Description

Technical Field

[0001] This invention relates to the field of boiler combustion technology, and in particular to a method for adjusting primary air velocity. Background Technology

[0002] The cold-state leveling test of the primary air velocity in a pulverized coal boiler is crucial for boiler combustion. Poor air velocity leveling is detrimental to pulverized coal combustion, leading to anything from high carbon content in fly ash and reduced boiler efficiency to more serious issues such as pulverized coal accumulation and blockage in the pulverized coal tubes, overheating of the heating surfaces causing high-temperature corrosion, and flame scorching due to combustion center misalignment, resulting in widespread coking. All of these seriously threaten the safe operation of the boiler. Therefore, a cold-state primary air velocity leveling test is generally required before boiler ignition and startup. The quality of this test directly affects the boiler's safety and economic efficiency.

[0003] The purpose of primary air leveling is to ensure that the primary air velocity deviation of the same burner layer is within a reasonable range, guaranteeing uniform heat load for the burners corresponding to the primary air, thereby balancing the steam parameters on both sides of the boiler. According to the requirements of the standard "DL / T 467-2004 Performance Test of Power Plant Coal Mill and Pulverizing System", if the primary air velocity deviation of the same burner layer is <15%, it indicates that the air volume distribution characteristics of the primary air duct are good and no adjustment is needed; if the velocity deviation is >15%, primary air leveling is required to bring the primary air velocity deviation within 15%.

[0004] The boiler has 5 to 6 layers of burners. Current technology for primary air leveling only considers controlling the deviation of primary air in the same layer of burners to within 15%. If the deviation of each layer of combustion zone is qualified, but the cumulative deviation of 5 or 6 layers of burners is concentrated in the same or similar positions in each layer, then the cumulative heat load deviation in the furnace will be large, making it difficult to achieve the effect of primary air leveling. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the aforementioned existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a primary air velocity leveling method to solve the problem that existing primary air velocity leveling methods cannot guarantee the uniformity of combustion in the boiler furnace.

[0008] To solve the above technical problem, the present invention provides the following technical solution, comprising: measuring the primary air velocity corresponding to burners at the same layer, and calculating the percentage of wind velocity deviation; repeating the calculation step, measuring and calculating the primary air velocity corresponding to each layer of burners, calculating the deviation, and arranging the deviation of each layer in a table; performing layered leveling on the primary air velocity corresponding to each layer of burners; performing regional leveling according to the different position regions of the primary air velocity in the furnace; determining symmetrical regions according to the physical positions of the burners, and checking the deviation of the symmetrical regions.

[0009] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: when measuring the primary air velocity corresponding to burners at the same layer, at the air velocity measuring hole of the primary air pipe corresponding to the burner, a calibrated and qualified S-type pitot tube is used to measure the differential pressure at each measuring point according to the equal-section grid method; the true dynamic pressure at each point and the average dynamic pressure in the pipe are obtained through conversion by the air volume coefficient of the S-type pitot tube, then the air velocity V of each primary air pipe at the outlet of the coal mill is calculated through the dynamic pressure, and the percentage of wind velocity deviation is calculated.

[0010] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: the primary air velocities corresponding to the first layer of burners are V11, V12, .....V1X; the average primary air velocity of the first layer of burners is V1=(V11+V12+.....+V1X) / X; then the percentage of wind velocity deviation of the burner at position No. X in the first layer is δ1x=V1x / V1.

[0011] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: repeating the calculation of the percentage of wind velocity deviation of each layer of burners, measuring and calculating the primary air velocity corresponding to each layer of burners, calculating the deviation, and arranging the deviation of each layer in a table.

[0012] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: adjusting the pipeline wind velocity with primary air velocity deviation δ>15% of each layer of burners, to ensure that all primary air deviations δ11→δXX are all <15%.

[0013] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: increasing or decreasing the primary air velocity by adjusting the size of the adjustable orifice on the primary air pipe.

[0014] As a preferred solution of the primary air velocity leveling method according to the present invention, wherein: according to the positions of the burners in the furnace, dividing the burners into a left region and a right region according to their positions in the furnace; summing the percentages of primary air deviation of the burners in each region, if the difference between the summation results is <D, it indicates that the regional leveling result meets the requirement; if the difference is greater than D, selecting the primary air velocity of the pipeline with the largest δ value in the region for readjustment, recalculating the δ value of the primary air deviation at the same layer after adjustment, until the regional deviation is within D, wherein D≤15%.

[0015] As a preferred embodiment of the primary wind speed leveling method described in this invention, in which: based on the regional leveling satisfying less than D, symmetrical regions are further determined according to the physical location of the burner, and the deviation of the symmetrical regions is checked; D≤15%.

[0016] As a preferred embodiment of the primary wind speed leveling method of the present invention, the method includes: a measurement module, which is set inside the multi-layer burner, for measuring the primary wind speed and calculating the percentage of wind speed deviation; and a leveling module, which performs layer-by-layer and area-by-area leveling of the primary wind speed corresponding to each layer of burner, and determines symmetrical areas according to the physical location of the burners, and performs deviation verification on the symmetrical areas.

[0017] A computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 8.

[0018] The beneficial effects of this invention are as follows: This invention adjusts the primary air velocity deviation to a reasonable level by calculating and adjusting the percentage of air velocity deviation, significantly improving the effect of primary air leveling. This can significantly improve the uniformity of the boiler furnace heat load, ensure that the steam parameters on the left and right sides of the boiler outlet are consistent, and reduce the boiler's thermal deviation. At the same time, this method keeps the primary air velocity deviation of the same layer of burners within a reasonable range, ensuring the uniform heat load of the burners corresponding to the primary air, thereby balancing the steam parameters on the left and right sides of the boiler. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below 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 effort. Wherein:

[0020] Figure 1 This is an adjustment diagram of the primary air duct and adjustable orifice according to an embodiment of the present invention;

[0021] Figure 2 This is a diagram of the primary air-adjusting furnace partitions as described in an embodiment of the present invention;

[0022] Figure 3 This is a primary air verification furnace partition diagram according to an embodiment of the present invention; Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0027] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1

[0030] Reference Figure 1 and Figure 2This is the first embodiment of the present invention, which provides a primary wind speed leveling method, comprising:

[0031] S1: Measure the primary wind speed corresponding to the burners in the same layer and calculate the percentage of wind speed deviation.

[0032] The primary air velocity corresponding to the burners on the same floor of the boiler is measured. At the airflow measurement port of the primary air duct corresponding to the burner, a calibrated back-to-back velocity measuring tube is used to measure the differential pressure at each measuring point using the equal cross-section grid method. The actual dynamic pressure at each point and the average dynamic pressure inside the tube are calculated using the airflow coefficient of the back-to-back tube. The air velocity V of each primary air duct at the coal mill outlet is calculated using the dynamic pressure, and the percentage deviation of the air velocity is calculated, such as:

[0033] The first-stage burner corresponds to primary air velocities of V11, V12, ..., V1X.

[0034] The average primary air velocity of the first-stage burner is V1 = (V11, V12, ..., V1X) / X

[0035] The percentage deviation of wind speed for the burner at position X in the first layer is δ1x = V1x / V1.

[0036] S2: Repeat the calculation steps, measure and calculate the primary wind speed corresponding to each layer of burners, calculate the deviation, and arrange the deviations of each layer in a table.

[0037] Repeat the first step to measure and calculate the primary wind speed for each burner layer, and calculate the deviation. Arrange the deviations for each layer in the table below.

[0038] S3: Level the primary air velocity corresponding to each layer of burner in layers.

[0039] For each burner layer, adjust the duct velocity where the primary air velocity deviation δ > 15% to ensure that all primary air velocity deviations δ11 → δXX are < 15% (<15% is the industry standard).

[0040] Adjustment method as follows Figure 1 As shown, the primary air velocity can be increased or decreased by adjusting the size of the adjustable orifice on the primary air duct.

[0041] S4: Different areas of the primary air velocity in the furnace are adjusted for different regions.

[0042] According to the positions of the burners in the furnace, the left-right deviation of the furnace heat load affects the steam parameters at the boiler outlet, while the front-rear deviation of the furnace has no influence on the steam parameters of the boiler. Therefore, the burners are divided into two left and right regions according to their positions in the furnace, and the percentages of primary air deviation of the burners in each region are summed. If the difference between the summation results is < D, it indicates that the regional leveling result meets the requirement; if the difference is greater than D, the primary air speed of the pipeline with the largest δ value in the region is selected for readjustment, and after adjustment, the δ value of primary air speed deviation in the same layer is calculated again until the deviation of the region is within 10%.

[0043] Regarding the selection of value D, D is an empirical value that needs to be selected according to the parameter deviation conditions of different boilers. Since the industry standard specifies that a primary air speed deviation of the same-layer burners less than 15% is qualified, D is generally selected to be less than or equal to 15%. If after selecting D as 15% in the fourth step, the furnace outlet temperatures on the left and right sides are balanced and the boiler steam parameters are also balanced, it indicates that 15% is appropriate; if there are still deviations in the boiler parameters, D is selected as 10% for adjustment, and so on.

[0044] S5: determining symmetrical regions according to the physical positions of the burners, and performing deviation check on the symmetrical regions.

[0045] On the basis that the zonal leveling meets the requirement of < D, symmetrical regions are further determined according to the physical positions of the burners, and deviation check is performed on the symmetrical regions. The check method is as follows: the deviation difference of the symmetrical regions is required to be < D, which functions as further fine adjustment of the deviation.

[0046] The selection of value D is the same as that described in S4.

[0047] Finally, the present invention solves the problem that the existing primary air speed leveling methods cannot guarantee the combustion uniformity in the boiler furnace, resulting in large deviation of steam parameters at the boiler outlet by disclosing a primary air speed leveling method. Through five-step adjustment, the primary air speed deviation is adjusted to a reasonable level, which greatly improves the effect of primary air speed leveling; the method provided by the present invention can significantly improve the uniformity of heat load in the boiler furnace, ensure that the steam parameters on the left and right sides of the boiler outlet are consistent, and reduce the heat deviation of the boiler.

[0048] Embodiment 2

[0049] In order to verify and illustrate the technical effects adopted in the method, the present embodiment selects a data test mode and compares the test results by means of scientific demonstration to verify the real effects of the method.

[0050] Step 1: Measure the primary air velocity corresponding to the same layer of burners. At the air flow measuring hole of the primary air pipe corresponding to the burner, a calibrated Pitot static tube (backrest velocity tube) is used to measure the differential pressure at each measuring point according to the equal-section grid method. The true dynamic pressure at each point and the average dynamic pressure in the pipe are obtained by conversion through the air flow coefficient of the backrest tube. The wind speed V of each primary air pipe at the outlet of the coal mill is calculated through the dynamic pressure, and the wind speed deviation percentage is calculated, for example:

[0051] The primary air velocities corresponding to the first layer of burners are V11, V12, .....V1X;

[0052] The average primary air velocity of the first layer of burners is V1=(V11、V12、.....V1X) / X;

[0053] Then the wind speed deviation percentage of the burner at the No. X position of the first layer is δ1x=V1x / V1; as shown in the table below:

[0054]

[0055] Step 2: Repeat the procedure of Step 1, measure and calculate the primary air velocity corresponding to each layer of burners, and calculate the deviation. Arrange the deviations of each layer as shown in the table below:

[0056]

[0057] Step 3: Leveling by layer

[0058] Adjust the pipe wind speed for each layer of burners where the primary air speed deviation δ>15%, to ensure that all primary air deviations δ11→δXX are all <15%. (<15% is the industry standard)

[0059] The adjustment method is as Figure 1 shown: the primary air flow velocity is increased or decreased by adjusting the opening size of the adjustable orifice on the primary air pipe.

[0060] Step 4: Leveling by sub-region

[0061] According to the positions of the burners in the furnace, the left-right deviation of the furnace heat load affects the steam parameters at the boiler outlet, while the front-back deviation of the furnace has no influence on the steam parameters of the boiler. Therefore, the burners are divided into left and two regions according to their positions in the furnace. Sum the primary air deviation percentages of the burners in each region. If the difference between the summation results is <D, it indicates that the regional leveling result meets the requirements; if it is greater than D, select the pipe with the largest δ value in the region to adjust the primary air velocity again, and recalculate the δ value of the primary air velocity of the same layer after adjustment until the deviation of the region is within 10%.

[0062] Regarding the selection of value D, D is an empirical value that needs to be selected according to the parameter deviation conditions of different boilers. Since the industrial standard specifies that the deviation of the primary air velocity of burners on the same layer is qualified when it is less than 15%, value D is generally selected to be less than or equal to 15%. If after selecting 15% as D in the fourth step, the furnace outlet temperatures at the left and right sides are balanced and the boiler steam parameters are also balanced, it indicates that 15% is appropriate. If there are still deviations in the boiler parameters, select 10% as D for adjustment, and so on.

[0063] Example description: (10% is selected as value D)

[0064] For a furnace with corner-fired tangential combustion, the four positions of the burners are shown in Figure 1 . In consideration of furnace combustion balance, the burners need to be divided into two regions, namely the left region and the right region: position 1 and position 4 belong to the left region, and position 2 and position 3 belong to the right region, as shown in Figure 2 .

[0065]

[0066] That is, if |∑δ1-∑δ2| < 10%, the regional leveling is qualified; if |∑δ1-∑δ2| > 10%, the primary air velocity with the largest δ value in the region is selected for readjustment. After adjustment, the deviation δ value of primary air velocity on the same layer is recalculated until the deviation of the region is within 10%.

[0067] For a furnace with dual-corner tangential combustion, it is similar to the aforementioned single-tangential furnace, and the left and right tangential combustion circles are divided into two regions, left and right, based on the principle of left-right combustion balance.

[0068] Step 5: Regional Check

[0069] After the regional leveling meets the requirement of being less than D, symmetric regions are further determined according to the physical positions of the burners, and deviation check is performed on the symmetric regions. The check method is as follows: the deviation difference between symmetric regions is required to be less than D, which functions as further fine adjustment of the deviation.

[0070] The selection of value D in step 5 is the same as that described in step 4.

[0071] Example description: (10% is selected as value D)

[0072] For a corner-fired tangential furnace, it is necessary to maintain left-right combustion balance. Therefore, after summing δ values by regions (region 1, region 2, region 3, region 4), check the deviation of symmetric regions: the deviation (of ∑δ1 and ∑δ2, or ∑δ3 and ∑δ4) is less than 10%, as shown in Figure 3 ,

[0073]

[0074] That is |∑δ1-∑δ2| < 10% and |∑δ3-∑δ4| < 10%.

[0075] For a double-corner tangent furnace, similar to the single-tangent furnace described above, burners at the same position in different layers are treated as a region, and regions at symmetrical positions on the left and right are selected for deviation verification to ensure that the deviation is less than 10%.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for leveling primary wind speed, characterized in that, include: Measure the primary air velocity corresponding to the burners on the same floor and calculate the percentage of air velocity deviation; Repeat the calculation steps, measure and calculate the primary wind speed corresponding to each layer of burners, calculate the deviation, and arrange the deviations of each layer in a table; The primary air velocity corresponding to each layer of burner is adjusted and leveled in layers. The primary air velocity is adjusted in different regions of the furnace according to its location; Determine the symmetrical region based on the physical location of the burner, and then check the deviation of the symmetrical region. According to the position of the burner in the furnace, the burner is divided into two areas, left and right, based on its position in the furnace. Sum the percentage of primary air deviation for each zone burner; If the difference between the summation results is less than D, then the regional leveling result meets the requirements. If the difference between the summation results is greater than D, then the primary wind speed of the pipe with the largest δ value in this area is selected for further adjustment. After adjustment, recalculate the primary wind speed deviation δ value at the same level until the deviation in this area is within D. Where D≤15%; If the regional leveling is less than D, then further determine the symmetrical region according to the physical location of the burner, and check the deviation of the symmetrical region; Where D≤15%; The primary air velocity corresponding to the burner on the same layer is measured. The differential pressure at each measuring point is measured using a calibrated back-to-back velocity measuring tube with equal cross-section grid method at the air volume measuring hole of the primary air duct corresponding to the burner. The actual dynamic pressure at each point and the average dynamic pressure inside the pipe are calculated by converting the air volume coefficient of the back pipe. Then, the wind speed V of each primary air duct at the outlet of the coal mill is calculated by the dynamic pressure, and the percentage of wind speed deviation is calculated. The percentage of wind speed deviation includes... The first-stage burner corresponds to primary air velocities of V11, V12, ..., V1X; The formula for the average primary air velocity of the first-stage burner is: V1=(V11, V12,...V1X) / X The formula for the percentage deviation of the wind speed of the burner at position X in the first layer is as follows: δ1x = V1x / V1; The percentage of wind speed deviation includes... Repeatedly calculate the percentage deviation of the wind speed for each layer of burners, measure and calculate the primary wind speed corresponding to each layer of burners, and calculate the deviation. Arrange the deviations for each layer in a table. If the primary air velocity deviation of the burner is greater than 15%, the air velocity in its duct should be adjusted. Conversely, it remains unchanged, ensuring that all primary wind deviations δ11→δXX are <15%.

2. The primary wind speed leveling method as described in claim 1, characterized in that: The primary air velocity can be increased or decreased by adjusting the size of the adjustable orifice on the primary air duct.

3. A boiler burner wind speed leveling system, employing the primary wind speed leveling method as described in any one of claims 1 to 2, characterized in that, include: The measurement module, installed inside the primary air duct, is used to measure the primary air velocity and calculate the percentage of air velocity deviation. The leveling module performs layer-by-layer and zone-by-zone leveling of the primary air velocity corresponding to each layer of burners, and determines symmetrical areas according to the physical location of the burners, and performs deviation verification on the symmetrical areas.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 2.

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