Coal-fired boiler ash conveying system and method for calculating ash conveying amount thereof

Abstract

The application discloses a coal-fired boiler ash conveying system and a method for calculating the conveying amount of the ash, and the compressed air conveying pipeline system comprises a compressed air main pipe, a first air branch pipe and a second air branch pipe, a first thermometer is fixedly installed on the compressed air main pipe, and the compressed air main pipe is extended to be connected with the first air branch pipe and the second air branch pipe; a pressure gauge and a flowmeter are fixedly installed on the first air branch pipe; the second air branch pipe is connected with an ash conveying pipe; a plurality of bin pumps are arranged on the ash conveying pipe in communication with the ash conveying pipe; a flowmeter is installed on the ash conveying pipe upstream of the first bin pump; a pressure gauge is arranged on the ash conveying pipe between any two bin pumps; a pressure gauge is installed at the input end entrance of the ash conveying pipe; and a second thermometer and a pressure gauge are sequentially installed on the output end of the ash conveying pipe; the ash amount is estimated through a calculation formula and experimental measurement values, and then the conveying period of the ash can be controlled to save energy and reduce consumption.

Description

Technical Field

[0001] This invention relates to an ash conveying system for a coal-fired boiler and a method for calculating the amount of ash conveyed, belonging to the field of boiler ash conveying. Background Technology

[0002] Currently, ash removal and conveying systems in large coal-fired boilers mostly employ pneumatic conveying. For electrostatic precipitators, ash is typically discharged from ash hoppers connected in series in each electric field, usually with 4 to 5 electric fields. The ash discharge rate of each electric field decreases starting from the first electric field. Determining the ash discharge rate of each electric field (each ash hopper) is of great significance, for example, in judging the operating status of the electrostatic precipitator. Current equipment does not have this function.

[0003] CN213010753U discloses an ash conveying system for controlling the ash level in the ash hopper of an electrostatic precipitator in a power plant, belonging to the field of ash conveying control technology. This ash conveying system includes several ash conveying units, each including several ash hoppers. Each ash hopper is connected to a branch ash conveying pipe below it via a branch ash conveying pipe. One end of the branch ash conveying pipe is connected to the main ash conveying pipe, and the other end is connected to a compressed gas inlet pipe. A discharge valve is installed at one end of the branch ash conveying pipe, and an inlet valve is installed at the other end. An ash silo pump is fixedly installed on the branch ash conveying pipe. An ash discharge valve is installed on the pipe section between the ash silo pump and the ash hopper, and a silo pump discharge valve is installed on the pipe section between the ash silo pump and the branch ash conveying pipe. A level gauge for monitoring the ash level is vertically fixedly installed inside each ash hopper. This invention arranges the ash conveying pipeline according to the different ash production rates of different electrostatic precipitators, eliminating system pipeline congestion and reducing energy and capital consumption.

[0004] Currently, existing technologies do not provide accurate calculations for ash conveying capacity. Therefore, we propose an ash conveying system for coal-fired boilers and a method for calculating ash conveying capacity, which addresses the aforementioned problems through effective system detection and scientific statistical calculation. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides an ash conveying system for a coal-fired boiler and a method for calculating the ash conveying capacity.

[0006] The technical solution of the present invention is as follows:

[0007] A coal-fired boiler ash conveying system and a method for calculating the ash conveying capacity are disclosed. The system includes a compressed air transmission pipeline system, several pressure gauges, several flow meters, and an ash conveying pipe. The compressed air transmission pipeline system includes a compressed air main pipe, a first air branch pipe, and a second air branch pipe. A first thermometer is fixedly installed on the compressed air main pipe. The compressed air main pipe extends and connects to the first and second air branch pipes. A pressure gauge and a flow meter are fixedly installed on the first air branch pipe. The second air branch pipe connects to the ash conveying pipe. Several silo pumps are connected to the ash conveying pipe. An air flow meter is installed on the ash conveying pipe upstream of the first silo pump. A pressure gauge is installed on the ash conveying pipe between any two silo pumps. A pressure gauge is installed at the inlet of the ash conveying pipe, and a second thermometer and a pressure gauge are sequentially installed at the outlet of the ash conveying pipe. A volume measuring instrument is installed on each silo pump.

[0008] Preferably, the hopper is connected to the upper inlet of the silo pump, and a feed valve is provided at the inlet.

[0009] Preferably, the first air branch pipe extension is connected to the main body of the silo pump, and an air inlet valve is provided on the branch pipe.

[0010] Preferably, the method for calculating the ash volume of the silo pump in a certain ash conveying cycle includes the following steps:

[0011] 1) Record the pressure measured by the pressure gauge before the ash enters the first silo pump as p0, the pressure measured by the pressure gauge before the second silo pump as p1, and the pressure measured by the pressure gauge before the nth silo pump as p n-1 The pressure measured by the subsequent pressure gauge is P. n Then, for the nth silo pump, its delivery pressure difference dp n =p n-1 -p n .

[0012] 2) Calculate the ash volume A for a certain ash conveying cycle of a certain silo pump using the following formula (I):

[0013] The amount of ash is:

[0014] In the formula dp n This represents the pressure difference in the ash hopper at the nth sampling point during the ash conveying cycle.

[0015] s is the shape correction factor, which is determined based on the waveform of the ash conveying pressure;

[0016] c is the conversion factor, which is determined experimentally.

[0017] f(t in ) is the compressed air temperature correction function at the inlet of the compressed air header, which is determined through experiments. The temperature t measured by the first thermometer (4) is used as the correction function. in Simply substitute it into the function expression;

[0018] g(f1) is the correction function for the air intake volume of the silo pump, which was determined through experiments;

[0019] h(f2) is the air intake correction function of the ash conveying pipe (12), which is determined through experiments;

[0020] i(t2) is the end air temperature correction function, which is determined by experiment. The temperature t2 measured by the second thermometer (5) can be substituted into the function.

[0021] Preferably, the method for determining the same ash amount is used to determine the total ash amount for any given ash conveying operation, i.e., the ash output from all ash hoppers on the ash conveying pipeline. In this case, dp n =p0-p n .

[0022] The present invention has the following beneficial effects: The present invention has a rationalized coal-fired boiler ash conveying system and its calculation method that saves energy and reduces consumption through precise instrument detection and scientific calculation using mathematical formulas; by measuring values ​​with instruments and substituting them into mathematical formulas to calculate the amount of coal ash, the air pressure is controlled according to the value to achieve the purpose of saving energy. Attached Figure Description

[0023] Figure 1 This is a system diagram of an ash conveying system for a coal-fired boiler and a method for calculating the ash conveying capacity, according to the present invention.

[0024] The attached figures are labeled as follows:

[0025] 1. Compressed air main pipe; 2. First air branch pipe; 3. Second air branch pipe; 4. First thermometer; 5. Second thermometer; 6. Pressure gauge; 7. Flow meter; 8. Inlet valve; 9. Ash hopper; 10. Feed valve; 11. Silo pump; 12. Ash conveying pipe; 13. Volume measuring instrument. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example:

[0028] See Figure 1A coal-fired boiler ash conveying system and a method for calculating the ash conveying capacity thereof, comprising a compressed air transmission pipeline system, several pressure gauges 6, several flow meters 7, and an ash conveying pipe 12. The compressed air transmission pipeline system includes a compressed air main pipe 1, a first air branch pipe 2, and a second air branch pipe 3. A first thermometer 4 is fixedly installed on the compressed air main pipe 1. The compressed air main pipe 1 extends and connects to the first air branch pipe 2 and the second air branch pipe 3 respectively. Pressure gauges 6 and flow meters 7 are fixedly installed on the first air branch pipe 2. The second air branch pipe 3 is connected to... Ash conveying pipe 12; several silo pumps 11 are connected to the ash conveying pipe 12. A flow meter 7 is installed on the ash conveying pipe 12 upstream of the first silo pump 11. A pressure gauge 6 is installed on the ash conveying pipe 12 between any two silo pumps 11. A pressure gauge 6 is installed at the inlet of the ash conveying pipe 12. A second thermometer 5 and a pressure gauge 6 are installed sequentially at the outlet of the ash conveying pipe 12. A volume measuring instrument 13, such as a laser level gauge, is installed on each silo pump 11. This instrument can be used during commissioning and removed after commissioning, or it can be retained for use during operation.

[0029] Furthermore, the hopper 9 is connected to the upper inlet of the silo pump 11, and a feed valve 10 is provided at the inlet.

[0030] Furthermore, the first air branch pipe 2 extends into a branch connected to the main body of the chamber pump 11, and an air inlet valve 8 is provided on the branch.

[0031] The method for calculating the ash volume of ash hopper 9 in a certain ash conveying cycle used in this invention is as follows:

[0032] 1) Record the pressure measured by pressure gauge 6 before the ash enters the first silo pump 11 as p0, the pressure measured by pressure gauge 6 before the second silo pump 11 as p1, and the pressure measured by pressure gauge 6 before the nth silo pump 11 as p n-1 The pressure measured by pressure gauge 6 is P. n Then, for the nth silo pump 11, its delivery pressure difference dp n =p n-1 -p n .

[0033] 2) Calculate the ash volume A of a certain ash conveying cycle of a certain silo pump 11 using the following formula (I):

[0034] The amount of ash is:

[0035] In the formula dp n This represents the pressure difference at the nth sampling point during the ash conveying cycle.

[0036] s is the shape correction coefficient, determined based on the waveform of the ash conveying pressure. If there are m pressure sampling points from the beginning to the end of the ash conveying cycle, then... During the calculation, it is required to keep other parameters constant. However, some parameters are actually uncontrollable. Multiple tests can be conducted while keeping the pressure and temperature as constant as possible to select the required data.

[0037] c is the conversion coefficient, determined experimentally. Once other functions are determined, this coefficient can be calculated based on the measured ash content Ah.

[0038] f(t in The function t is the correction function for the inlet compressed air temperature, determined experimentally. This function is usually the last to be determined. When determining other parameters, this temperature should be kept relatively constant and can be temporarily set to 1. Calculations based on measurements taken in both winter and summer will make the data more representative. In use, if there are multiple chamber pumps 11, to simplify the system, the temperature difference between the first thermometer 4 and the second thermometer 5 can be evenly distributed to determine the inlet air temperature t. in If the temperature change along the ash conveying pipe 12 is not significant, the temperature t measured by the first thermometer 4 can be used as the reference. in Simply substitute the values ​​into the function, and the outlet temperature t2 does not need to be corrected.

[0039] g(f1) is the correction function for the air intake of the silo pump. It was determined through experiments that the air intake of silo pump 11 is affected by the amount of ash. If there is a lot of ash in the ash hopper 9, the amount of air entering will be less. Multiple tests can be conducted while keeping the pressure and temperature as constant as possible to select the required data. Since the flow meter 7 is on the compressed air header 1, the air intake can be directly read from the flow meter 7 for tests on a single silo pump 11. For tests on multiple silo pumps 11 conducted simultaneously, if the operating parameters of each silo pump 11 are similar, the flow rate can be evenly distributed among each silo pump 11.

[0040] h(f2) is the correction function for the air intake of the ash conveying pipe. It was determined through experiments that the air intake of the ash conveying pipe 12 is actually uncontrollable during operation. Multiple tests can be conducted while keeping the pressure and temperature as constant as possible to select the required data.

[0041] i(t2) is the terminal air temperature correction function, which was determined through experiments. By taking measurements and calculating data in both winter and summer, the data can be made more representative. When determining other functions, it can be temporarily set to 1, and the temperature t2 measured by the second thermometer 5 can be substituted into the function formula.

[0042] In determining the above formula, the ash amount (i.e., the value of A) of each ash hopper 9 can be measured by a level gauge. After the test, the level gauge can be removed or retained depending on the actual situation. Furthermore, the level gauge can only be used to measure the ash level when the silo pump 11 is not discharging ash. When ash is discharging, the ash level boundary is unclear, making it impossible to measure the ash level, and it also cannot reflect the ash flow.

[0043] For cases where the level gauge is retained, the measurement information is incorporated into the corresponding computer system. If the measured ash amount is Ah, Ah / A is used as the judgment factor. If this value deviates too much from the normal value, it indicates that there is a problem with the ash conveying operation. This adds another means to judge whether the ash conveying is normal.

[0044] For cases where level gauges are removed, they can be periodically reinstalled to compare and correct the calculation results. If Ah / A deviates significantly from the normal value, it indicates a problem with the ash conveying process.

[0045] S (shape correction factor) can be used to judge the status of ash conveying operation. If this value deviates too much from the normal value, it means that there is a problem with the ash conveying operation.

[0046] For the sake of accuracy, the function described above can be expressed as, but is not limited to, a quadratic polynomial, i.e., f = a + a1x + a2x 2 The coefficients can be determined by fitting the samples obtained from the experiment. In most cases, this formula can meet the requirements. The number of times can be adjusted according to the actual situation, and the number can be increased or decreased according to the fitting accuracy.

[0047] Furthermore, the same method for determining ash quantity is used to determine the total ash quantity for any given ash conveying operation, i.e., the ash output from all ash hoppers on the ash conveying pipeline. In this case, dp n =p0-p n This refers to the pressure difference between the first silo pump 11 and the last silo pump 11; the calculation methods for other parameters are inconvenient.

[0048] Working principle of the invention:

[0049] refer to Figure 1This invention utilizes a compressed air transmission pipeline system, several pressure gauges 6, several flow meters 7, and an ash conveying pipe 12. The compressed air transmission pipeline system includes a compressed air main pipe 1, a first air branch pipe 2, and a second air branch pipe 3. Pressurized air is supplied from the end of the compressed air main pipe 1, and a first thermometer 4 is installed on the compressed air main pipe 1. The compressed air main pipe 1 extends and connects to the first air branch pipe 2 and the second air branch pipe 3. The extension branch of the first air branch pipe 2 is connected to the main body of the silo pump 11, and an air inlet valve 8 is provided on the branch. Pressure gauges 6 and flow meters 7 are fixedly installed on the first air branch pipe 2. The second air branch pipe 3 is connected to the ash conveying pipe. Pipe 12, the second air branch pipe 3 is connected to the ash conveying pipe 12; several silo pumps 11 are connected to the ash conveying pipe 12, a flow meter 7 is installed on the ash conveying pipe 12 upstream of the first silo pump 11, and a pressure gauge 6 is installed on the ash conveying pipe 12 between any two silo pumps 11; a pressure gauge 6 is installed at the inlet of the ash conveying pipe 12, and a second thermometer 5 and a pressure gauge 6 are installed sequentially at the outlet of the ash conveying pipe 12; the ash hopper 9 is connected to the upper inlet of the silo pump 11, and a feed valve 10 is installed at the inlet; a pressure gauge 6 is installed at the inlet of the ash conveying pipe 12, and a second thermometer 5 and a pressure gauge 6 are installed sequentially at the outlet of the ash conveying pipe 12; the value measured by the first thermometer 4 is t. in The value measured by the second thermometer 5 installed at the output end of the ash conveying pipe 12 is t2; the ash quantity calculation formula used in this invention is as follows:

[0050] The pressure before the first pump 11 is p0, the pressure before the second pump 11 is p1, and so on. The pressure before the nth pump 11 is p... n-1 The subsequent pressure is P n Then, for the nth silo pump 11, its delivery pressure difference dp n =p n-1 -p n .

[0051] The ash volume of a certain silo pump in a certain ash conveying cycle can be determined using the following method:

[0052] The amount of ash is:

[0053] In the formula dp k Let dp be the pressure difference at the k-th sampling point during the ash conveying cycle. Substituting the data measured above into the formula for calculation and correction yields the result. A larger ash volume value indicates a higher air pressure should be used; a smaller ash volume value indicates a smoother pipeline, allowing for the use of a lower air pressure. Based on this formula, when using the same ash volume method to determine the total ash volume for any given ash conveying cycle (i.e., the ash output from all ash hoppers on the ash conveying pipeline), dp is... n =p0-p n Simply substitute the values ​​into the formula to calculate.

[0054] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for calculating the amount of transported ash in an ash handling system of a coal-fired boiler, comprising a compressed air transport pipeline system, a number of pressure gauges (6), a number of flow meters (7) and an ash transport pipe (12), characterized in that: The compressed air transmission pipeline system comprises a compressed air main pipe (1), a first air branch pipe (2) and a second air branch pipe (3), a first thermometer (4) is fixedly installed on the compressed air main pipe (1), the compressed air main pipe (1) is extended to connect the first air branch pipe (2) and the second air branch pipe (3) respectively; a pressure gauge (6) and a flowmeter (7) are fixedly installed on the first air branch pipe (2); the second air branch pipe (3) is connected with a conveying ash pipe (12); a plurality of silo pumps (11) are arranged on the conveying ash pipe (12) and communicate with the conveying ash pipe (12); the flowmeter (7) is installed on the conveying ash pipe (12) upstream of the first silo pump (11); the pressure gauge (6) is arranged on the conveying ash pipe (12) between any two silo pumps (11); the pressure gauge (6) is installed at the input end entrance of the conveying ash pipe (12); the second thermometer (5) and the pressure gauge (6) are installed at the output end of the conveying ash pipe (12) in sequence; the volume measuring instrument (13) is installed on each silo pump (11); the ash bucket (9) is connected with the inlet of the silo pump (11), and the inlet is provided with the feeding valve (10); the calculation method of the ash amount of the ash bucket (9) in a certain conveying ash period comprises the following steps: 1) record the pressure p0 measured by the pressure gauge (6) before the ash enters the first bin pump (11), the pressure p1 measured by the pressure gauge (6) before the ash enters the second bin pump (11), and the pressure pn measured by the pressure gauge (6) before the ash enters the nth bin pump (11) n-1 , and the pressure P measured by the pressure gauge (6) after the ash enters the nth bin pump (11) n , then for the nth bin pump (11), the delivery pressure difference dp n = p n-1 - p n ; 2) the ash amount A of the silo pump (11) in a certain conveying ash period is calculated by using the following formula (I): Ash amount: A = B - C n s * c * f(t in ) * g(f1) * h(f2) * i(t2) where dp n is the pressure difference of the nth sampling point of the ash chute (9) in the ash conveying period. s is a shape correction coefficient, which is determined according to the waveform of the conveying ash pressure; c is a conversion coefficient, which is determined by experiment; f(t in ) is the compressed air temperature correction function of the compressed air main inlet, determined by experiment, and the temperature t in measured by the first thermometer (4) is substituted into the function expression. g(f1) is a silo pump air inlet amount correction function, which is determined by experiment; h(f2) is a conveying ash pipe (12) air inlet amount correction function, which is determined by experiment; i(t2) is a terminal air temperature correction function, which is determined by experiment, and the temperature t2 measured by the second thermometer (5) is substituted into the function formula.

2. The method of calculating the amount of ash to be transported in an ash handling system of a coal-fired boiler according to claim 1, characterized in that: The first air branch pipe (2) extends a branch pipe which communicates with the silo pump (11) main body, and the branch pipe is provided with the air inlet valve (8).

3. The method of calculating the amount of ash to be transported in an ash handling system of a coal-fired boiler according to claim 1, characterized in that: The method for determining the same amount of ash is used to determine the total amount of ash for each time of ash conveying, i.e. the amount of ash discharged from all ash hoppers on the ash conveying pipeline, at which time dp n = p0-p n , i.e. the pressure difference before the first bin pump and after the last bin pump.

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