An on-line working condition specific resistance testing device and method integrated with an electric dust collector

Abstract

The application belongs to the field of flue gas monitoring devices, and particularly discloses a working condition specific resistance online testing device and method integrated with an electric dust collector, which comprises a fly ash sampling end, a purging system and a working condition specific resistance measuring system, wherein: the fly ash sampling end is installed at the recess at the end of the anode plate of the electric dust collector; the fly ash sampling end comprises electrodes, the middle area formed by the two opposite electrodes is a dust accumulation area, and the bottom of the dust accumulation area is provided with an insulating movable baffle; the purging system is installed on the upper part of the fly ash sampling end and is used for purging and cleaning the dust in the fly ash sampling end when the insulating movable baffle is opened; and the working condition specific resistance measuring system is connected with the electrodes and is used for measuring the specific resistance in real time after the dust is accumulated. The application can realize real-time online measurement of the fly ash working condition specific resistance during the operation of the electric dust collector, and can be used for supporting online adjustment and optimization of high-voltage power supply parameters, so that the dust removal efficiency is ensured and energy saving is maximized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flue gas monitoring devices, and more particularly relates to a working condition specific resistance online testing device and method integrated with an electric dust collector. BACKGROUND

[0002] The electric dust collector is widely used in flue gas treatment in industries such as electric power and steel, and is particularly used in more than 70% of the units of coal-fired power plants. The specific resistance of fly ash is an important parameter affecting the performance of the electric dust collector. From the adaptability of the electric dust collector to dust, dust with specific resistance <10 4 Ω·cm is called low specific resistance dust, dust with specific resistance >10 11 Ω·cm is called high specific resistance dust (sometimes dust with specific resistance >10 12 Ω·cm is called high specific resistance dust), and dust with specific resistance in the range of 10 4 ~10 11 Ω·cm is called medium specific resistance dust. The specific resistance of dust directly affects the charging characteristics of dust. For medium specific resistance dust, the electric dust collector can achieve good dust removal effect. When the specific resistance of dust is too low, secondary dust raising is easy to occur, resulting in a decrease in dust removal efficiency. When the specific resistance of dust is too high, reverse corona is easy to occur, also resulting in a decrease in dust removal efficiency. Moreover, in the medium specific resistance range that is easy to electrically collect dust, the lower the specific resistance, the more conducive to dust removal. Real-time and accurate mastery of the specific resistance value of fly ash, and reasonable regulation and control of the electric control, ash conveying and other parameters of the electric dust collector based thereon, are conducive to maximizing the guarantee of dust removal efficiency and taking into account energy saving and safety. The existing fly ash specific resistance monitoring device is obtained by on-site sampling and laboratory determination, and the time is seriously lagged. Moreover, the sample is easy to be affected. Even if a portable working condition specific resistance tester is used, it can only test the high dust concentration environment at the inlet of the electric dust collector, and the operation is complex. If the sample is broken down due to non-standard operation, the data will be invalid. Moreover, manual cleaning of the circular electrode is required for each sample, which is tedious and inefficient, and cannot realize online tracking of the change of specific resistance. Especially in the case of multi-element heterogeneous fuel blending, real-time online working condition specific resistance is urgently needed in coal-fired power plants. SUMMARY

[0003] In view of the above defects or improvement needs of the prior art, the present application provides a working condition specific resistance online testing device and method integrated with an electric dust collector, which aims to realize real-time online determination of the working condition specific resistance of fly ash during the operation of the electric dust collector, so as to maximize energy saving while ensuring dust removal efficiency.

[0004] To achieve the above-mentioned purpose, according to one aspect of the present application, a working condition specific resistance online testing device integrated with an electric dust collector is provided, which comprises a fly ash sampling end, a purging system and a working condition specific resistance determination system, wherein:

[0005] The fly ash sampling end is installed at the end groove of the anode plate of the electric dust collector; the fly ash sampling end comprises electrodes, and the middle area formed by the two opposite electrodes is a dust accumulation area, and the bottom of the dust accumulation area is provided with an insulating movable baffle;

[0006] The blowing system is installed on the upper part of the fly ash sampling end, and is used for blowing and cleaning the dust in the fly ash sampling end when the insulating movable baffle is opened;

[0007] The working condition specific resistance measuring system is connected with the electrodes, and is used for measuring the specific resistance in real time after the dust accumulation area is full of dust.

[0008] As a further optimization, there are several electric fields in the electric dust collector, and the fly ash sampling end is arranged on the second anode plate of each electric field; and the height of the fly ash sampling end on the anode plate is lowered in sequence from the inlet to the outlet of the electric field.

[0009] As a further optimization, the periphery of the two electrodes is provided with insulating material, the material of the insulating movable baffle and the insulating material is polytetrafluoroethylene, and the material of the electrode is stainless steel.

[0010] As a further optimization, the blowing system comprises a nozzle, a compressed air pipeline and an instrument compressed air storage tank, the instrument compressed air storage tank delivers air to the nozzle through the compressed air pipeline, and the nozzle is installed on the upper part of the fly ash sampling end at a distance of 8cm to 12cm.

[0011] As a further optimization, the working condition specific resistance measuring system comprises a fixed resistance and a direct current power supply, and the direct current power supply is connected with the fixed resistance and the electrodes in sequence.

[0012] As a further optimization, a data control system is further included, which is connected with the working condition specific resistance measuring system, is used for analyzing the specific resistance data, and adjusts the operation parameters of the power supply according to the specific resistance data, and the power supply is used for supplying power to the electric field in the electric dust collector.

[0013] According to another aspect of the present application, a working condition specific resistance online testing method is provided, which is realized by using the above-mentioned working condition specific resistance online testing device integrated with the electric dust collector, and comprises the following steps:

[0014] After the dust accumulation area is full of dust, the measured specific resistance is R measured by the working condition specific resistance measuring system. s ;

[0015] The insulating movable baffle is opened, the dust in the fly ash sampling end is blown and cleaned by the blowing system, and the no-load resistance value R0 is measured by the working condition specific resistance measuring system;

[0016] According to the measured specific resistance meter R s And the no-load resistance value R0 to calculate the working condition specific resistance.

[0017] As a further preferred, the formula for calculating the working condition specific resistance R is as follows:

[0018]

[0019] Wherein, H is the thickness of the electrode, W is the length of the electrode, and L is the distance between the two electrodes.

[0020] As a further preferred, the purge pressure of the purge system is 0.3-1.0 MPa, and for the electric field from the inlet to the outlet, the corresponding purge pressure of the purge system decreases in turn; the dust blowing time of the purge system is consistent with the anode plate shaking time.

[0021] As a further preferred, the data control system adjusts the operating parameters of the power supply according to the working condition specific resistance calculated by it: for the last stage electric field near the outlet, the power supply voltage is proportional to the working condition specific resistance; for the remaining electric fields, the power supply field strength is proportional to the working condition specific resistance.

[0022] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0023] 1. The fly ash sampling end of the present application is installed in the high-efficiency dust collection area at the recessed groove of the anode plate end, and through the electric dust collection capacity of each electric field of the electric dust collector, the dust is accumulated to the sampling end, and the designed purge system can obtain the specific resistance value and the no-load resistance value when the dust is full, thereby realizing real-time online measurement of the fly ash working condition specific resistance during the operation of the electric dust collector.

[0024] 2. Since the amount of ash at the first anode plate in the electric field is less, and the dust concentration of the subsequent anode plates is reduced, in order to improve the measurement accuracy, the fly ash sampling end is arranged at the second anode plate of the electric field; at the same time, considering the change of the height of the dust in different electric fields of the dust collector, in order to ensure sufficient dust collection and avoid the influence of the top block of the shaking dust layer on sampling, the height of the fly ash sampling end on the anode plate is designed.

[0025] 3. According to the real-time online measurement of the specific resistance value, the electric control parameters are adjusted, the ash hopper level is monitored, the output of the ash conveying system is adjusted, the dust removal efficiency is ensured, energy saving and safety are realized, the operation optimization and the effect of synergistic effect of pollution reduction and carbon reduction are realized. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The structure diagram of the working condition specific resistance online testing device of the embodiment of the present application;

[0027] Figure 2 The side view of the electric dust collector installed with the working condition specific resistance online testing device according to the embodiment of the present application;

[0028] Figure 3 The top view of the electric dust collector installed with the working condition specific resistance online testing device according to the embodiment of the present application.

[0029] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein: 1 - fly ash sampling end, 2 - electrode, 3 - insulating plate, 4 - working condition specific resistance measuring system, 5 - insulating pad, 6 - insulating movable baffle, 7 - pneumatic transmission shaft, 8 - compressed air pipeline, 9 - nozzle, 10 - purging system, 11 - anode plate, 12 - fixed resistor, 13 - direct current power supply, 14 - calibration resistor, 15 - temperature and humidity testing system, 17 - centralized control system, 18 - power supply, 19 - inlet head, 20 - outlet head, 21 - ash hopper, 22 - ash conveying system. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0031] The working condition specific resistance online testing device integrated with the electric dust collector according to the embodiment of the present application, as shown in Figure 1 includes a fly ash sampling end 1, a purging system 10, a working condition specific resistance measuring system 4, and a data control system 17, wherein:

[0032] The fly ash sampling end 1 includes a recess at the end of the anode plate of the electric dust collector, which is used to periodically collect fly ash samples; the fly ash sampling end 1 includes an electrode 2, an insulating pad 5, an insulating plate 3, and an insulating movable baffle 6, and the middle area formed by the two opposite electrodes 2 is a dust accumulation area; the insulating pad 5 and the insulating plate 3 are jointly arranged around the two electrodes 2, and the insulating movable baffle 6 is located below the dust accumulation area and can be controlled to open and close by the pneumatic transmission shaft 7.

[0033] Preferably, the electric dust collector has a plurality of electric fields, and at least three fly ash sampling ends 1 and their matched measuring systems are arranged in each electric field, and the fly ash sampling end 1 is arranged at the high-efficiency dust collection area of the recess at the end of the second anode plate of each electric field; for the primary electric field at the inlet to the last electric field at the outlet, the height of the fly ash sampling end on the anode plate decreases in turn, and the measurement time period increases in turn.

[0034] In one embodiment, as Figure 2and Figure 3 As shown in the figure, there are four electric fields in the electric dust collector. In order to ensure sufficient dust collection and avoid the influence of the rapping dust layer on the sampling, the fly ash sampling end of different electric fields is arranged at different heights of the anode plate. The first to fourth electric fields are arranged at 1 / 3, 1 / 2, 2 / 3 and 3 / 4 of the top end, respectively.

[0035] Preferably, the thickness H of the electrode is 5-15 mm, the length W of the electrode is 80-120 mm, and the distance L between the two electrodes is 5-15 mm. Meanwhile, the thickness of the electrode gradually decreases from the primary electric field to the final electric field, and the distance between the two electrodes gradually decreases.

[0036] Preferably, the materials of the insulating pad 5, the insulating plate 3 and the insulating movable baffle 6 are polytetrafluoroethylene, and the material of the electrode 2 is stainless steel.

[0037] The blowing system 10 is installed on the upper part of the fly ash sampling end 1, and includes a nozzle 9, a compressed air delivery pipeline 8 and a supporting instrument compressed air storage tank connected in sequence, etc., for periodically blowing the accumulated powder cake layer of the fly ash sampling end 1.

[0038] Preferably, the blowing system 10 is arranged at 8-12 cm (further preferably 10 cm) of the upper part of the fly ash sampling end 1, the blowing pressure is controlled at 0.3-1.0 MPa, and the blowing pressure gradually decreases from the primary electric field to the final electric field. The compressed air used is instrument compressed air after water and oil removal.

[0039] The working condition specific resistance measuring system 4 includes a fixed resistance 12, a direct current power supply 13, a calibration resistance 14, and a current meter and a voltage meter matched therewith, for periodically measuring the working condition specific resistance of the powder cake layer and automatically calibrating the system.

[0040] Specifically, the fly ash sampling end 1 in the working condition specific resistance measuring system 4 is taken as a dust specific resistance unit to be tested, the electrode 2 thereof is connected in series with the fixed resistance 12 to prevent the sample from being broken down when the direct current power supply 13 supplies power unstably, the dust specific resistance value is converted through the equipped voltage and current, and the system is calibrated through the calibration resistance 14 as needed.

[0041] The data control system 17 is used for specific resistance data analysis and display, and generates a recommended control strategy of the power supply 18 parameters on this basis. The power supply 18 is a high-voltage power supply, which is used for supplying power to each electric field in the electric dust collector.

[0042] The working condition specific resistance online testing device is used for working condition specific resistance online testing, including the following steps:

[0043] After the dust in the fly ash sampling end 1 is accumulated to be full, the working condition specific resistance measuring system 4 starts the specific resistance testing function, and the measured specific resistance is Rs ;

[0044] Then the pneumatic rotating shaft 7 is automatically started, the insulating movable baffle 6 is opened, the blowing system 10 is synchronously opened, the dust in the fly ash sampling end 1 is cleaned, and the dust is emptied again to start the test, and the emptying is calculated as the resistance value R0; the cleaning time in the fly ash sampling end 1 should be consistent with the time of the anode plate vibration.

[0045] Further, the formula for calculating the working condition specific resistance R is as follows:

[0046]

[0047] In the formula, H is the thickness of the electrode, W is the length of the electrode, and L is the distance between the two electrodes.

[0048] Further, the data control system 17 accurately controls the operating parameters of the power supply 18 of each electric field based on the measured specific resistance data of each electric field; specifically, the specific resistance value of the last-stage electric field is proportional to the supply voltage, and the charging capacity of the high specific resistance dust is improved by increasing the peak voltage; and the specific resistance value of each preceding-stage electric field is proportional to the supply field strength, and when the specific resistance is increased, a greater energy flux density is provided by increasing the supply current.

[0049] Further, according to the specific resistance change and the adjustment of the electric control parameter, the material level under the electric field is reasonably monitored and the output of the ash conveying system 22 is adjusted, and the smooth conveying of the first electric field is mainly ensured to ensure safe and reliable operation.

[0050] In addition, the present application also provides an accuracy verification method for the working condition specific resistance test result, which specifically installs a temperature and humidity test system 15 in the fly ash sampling end 1, which includes a temperature and humidity sensor arranged in the electric field, which is used to collect the smoke property parameters in real time, and the determination trigger time is consistent with the test time of the specific resistance measurement. At the same time, a coal and fly ash composition reporting system is set in the data control system 17, which is combined with SO3 online test data, and the fly ash working condition specific resistance is calculated by data fitting, and compared with the online test value.

[0051] The calculation method of the fly ash working condition specific resistance comprises the following steps:

[0052] (1) The fly ash volume specific resistance and surface specific resistance are calculated by the following formula:

[0053] ρ v =exp(-1.8916 ln X-0.9696 ln Y+1.237 ln Z+3.62876-0.069078 E+9980.58 / T)

[0054] ρ s= exp[27.59774-2.233348ln X-0.00176 W-0.069078 E-0.00073895 W exp(2303.3 / T)]

[0055] In the formula, ρ v , ρ s are the volume resistivity and surface resistivity (Ω·cm) of fly ash, respectively; X, Y, Z are the atomic mass fractions (%) of Li+Na, Fe, Mg+Ca, respectively; E is the electric field intensity (kV / cm); T is the temperature (K); and W is the water vapor content (%).

[0056] (2) When Z>3.5% or K<1.0% (K is the atomic mass fraction of potassium), the total resistivity calculation formula is:

[0057]

[0058] (3) When the working condition resistivity needs to consider the influence of fly ash surface deposited sulfuric acid mist on the resistivity, the correction amount can be expressed by the following formula:

[0059]

[0060] wherein, represents the SO3 concentration value (mg / m 3 ) in the flue gas.

[0061] At this time, the working condition resistivity calculation formula is:

[0062]

[0063] In summary, compared with the traditional portable off-line working condition resistivity testing device and the laboratory resistivity testing platform, the present application can realize real-time online measurement of fly ash working condition resistivity during the operation of the electric precipitator, and can be used to support online adjustment and optimization of high-voltage power supply parameters, to ensure the dust removal efficiency while maximizing energy saving.

[0064] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An online testing device for working condition specific resistance integrated with an electrostatic precipitator, characterized in that: The system comprises a fly ash sampling terminal (1), a purge system (10), an operating condition specific resistance measurement system (4) and a data control system (17), wherein: The fly ash sampling end (1) is installed at the end groove of the anode plate (11) of the electrostatic precipitator; the fly ash sampling end (1) includes an electrode (2), and the middle area formed by the two opposing electrodes (2) is a dust accumulation area, and an insulating movable baffle (6) is provided at the bottom of the dust accumulation area; There are several electric fields in the electrostatic precipitator, and the fly ash sampling end (1) is arranged on the second anode plate of each electric field; and for the electric field from the inlet to the outlet, the height of the fly ash sampling end (1) on the anode plate decreases successively; The purge system (10) is installed on the upper part of the fly ash sampling end (1) and is used to purge and clean the dust in the fly ash sampling end (1) when the insulating movable baffle (6) is opened; The working condition specific resistance measuring system (4) is connected to the electrode (2) and is used to measure the specific resistance in real time after the dust is fully accumulated in the dust accumulation area; The data control system (17) is connected to the working condition specific resistance measurement system (4) and is used to analyze specific resistance data and adjust the operating parameters of the power supply (18) accordingly. The power supply (18) is used to power the electric field in the electrostatic precipitator.

2. The online testing device for specific resistance under working condition integrated with an electrostatic precipitator according to claim 1, characterized in that: Insulating material is provided around the two electrodes (2); the material of the insulating movable baffle (6) and the insulating material are polytetrafluoroethylene; and the material of the electrodes (2) is stainless steel.

3. The online testing device for working condition specific resistance integrated with an electrostatic precipitator according to claim 1, characterized in that: The purge system (10) comprises a nozzle (9), a compressed air pipeline (8) and an instrument compressed air storage tank. The instrument compressed air storage tank delivers air to the nozzle (9) through the compressed air pipeline (8). The nozzle (9) is installed 8 cm to 12 cm above the fly ash sampling end (1).

4. The online testing device for specific resistance under working condition integrated with an electrostatic precipitator according to claim 1, characterized in that: The working condition specific resistance measuring system (4) comprises a fixed resistor (12) and a DC power supply (13), wherein the DC power supply (13) is sequentially connected in series with the fixed resistor (12) and the electrode (2).

5. A method for online testing of specific resistance under working conditions, implemented by using the online testing device for specific resistance under working conditions integrated with an electrostatic precipitator according to any one of claims 1 to 4, characterized in that: The steps include: When the dust accumulation area is full, the measured specific resistance is measured by the working condition specific resistance measurement system (4) and is R s ; The insulating movable baffle (6) is opened, and the purge system (10) is used to purge and clean the dust in the fly ash sampling end (1), and the no-load resistance value R0 is measured by the working condition specific resistance measurement system (4); According to the measured specific resistance, R s The working condition specific resistance is calculated by adding the no-load resistance value R0.

6. The online testing method for specific resistance under working conditions according to claim 5, characterized in that: The calculation formula of the working condition specific resistance R is as follows: Where H is the thickness of the electrode, W is the length of the electrode, and L is the distance between the two electrodes.

7. The online testing method for specific resistance under working conditions according to claim 5, characterized in that: The purge pressure of the purge system (10) is 0.3 MPa to 1.0 MPa, and the purge pressure of the corresponding purge system (10) decreases in sequence from the inlet to the outlet of the electric field; the time for the purge system (10) to perform dust purge is consistent with the anode plate vibration time.

8. The online testing method for specific resistance under working conditions according to any one of claims 5 to 7, characterized in that: The data control system (17) adjusts the operating parameters of the power supply (18) according to the calculated working condition specific resistance: for the final electric field near the outlet, the power supply voltage is proportional to the working condition specific resistance; for the remaining electric fields, the power supply field strength is proportional to the working condition specific resistance.

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