An online automatic dust resistivity measuring device

Abstract

This invention provides an online automatic measurement device for fly ash resistivity, employing a modular design. It includes a sampling system, an integrated ash removal and cleaning system, an electrode system, an automated control system, and other auxiliary equipment. The sampling system consists of a sampling head, a three-way sampling tube, and a connecting base. The measuring chamber comprises a base plate with a sliding groove, a top plate with an ash-flushing pipe, a tail plate with an exhaust pipe connector, and a front baffle with a connecting seat, along with a corresponding ash removal slide plate and a microporous ceramic filter plate. The ash removal port is located at the bottom of the device, allowing for easy return of the ash sample from the measuring chamber to the flue gas duct with the cleaning device, reducing secondary pollution. The electrode system consists of measuring electrodes and a bakelite base plate. The automated control system comprises a high-voltage power supply, a PLC, wires, an electric actuator, sensors within the flue gas duct, and a computer with an automatic resistivity calculation program. This device operates with a high degree of automation; sampling, measurement, data calculation, and ash removal are all executed by the PLC program, achieving online automatic detection of fly ash resistivity.

Description

Technical Field

[0001] This invention relates to an online measuring device for dust resistivity, and more particularly to an online measuring device for dust resistivity in the flue of an electrostatic precipitator. Background Technology

[0002] Although my country's economic development level has been improving year by year, the environmental situation has become increasingly severe. Faced with such severe environmental pressure, the country has proposed the concept of ultra-low emissions, and coal-fired power plants, as "major coal consumers," are the first to bear the brunt.

[0003] Currently, over 80% of coal-fired power plants in China use electrostatic precipitators (ESPs). As the dust removal principle of ESPs shows, the resistivity of the dust is a crucial parameter, affecting not only dust removal efficiency but also the applicability of the ESP. However, my country's coal types are complex and varied, with different resistivity values. The dust removal effect or adaptability of ESPs will differ significantly for different coal types. Even for the same coal type, the resistivity of the dust will fluctuate with changes in flue gas temperature, humidity, sulfur content, and other factors during actual operation. These fluctuations can deviate significantly from the design value, adversely affecting the operation and control of the ESP.

[0004] Therefore, real-time monitoring of dust resistivity is crucial for the safe and stable operation of electrostatic precipitators. Currently, most on-site dust resistivity measurement devices, both domestically and internationally, require dedicated personnel to temporarily install and measure the device on-site. Since only one set of data can be measured at a time, the installation and removal process must be repeated multiple times to improve measurement accuracy. This cumbersome process is not only time-consuming and labor-intensive but also seriously affects the operators' understanding of the true resistivity of the dust in the flue. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of complex on-site dust resistivity measurement devices and processes, and to achieve fully automated measurement technology for dust in flues, from sampling and measurement to ash removal. The entire measurement process requires no manual operation, improving measurement accuracy while transmitting data to the control center promptly and accurately. This not only saves labor but also allows operators to conveniently and quickly obtain the actual dust resistivity value in the flue, enabling them to take the most effective measures based on the measurement data, thereby greatly improving the operating performance of the electrostatic precipitator.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] An automated online resistivity testing device for fly ash employs a modular design, dividing the overall equipment into an electrode system, a sampling system, an automated control system, an integrated ash unloading and cleaning system, and other auxiliary equipment. The electrode system consists of measuring electrodes and a bakelite base plate; the stainless steel measuring electrodes are fixed to pre-drilled grooves in the bakelite base plate with screws. The sampling system comprises a sampling head, a three-way sampling tube, and a connecting base. The integrated ash unloading and cleaning system is the main component of the dual-measuring chamber. Each measuring chamber consists of a base plate with a sliding groove, a top plate with a flushing pipe, a tail plate with an exhaust pipe connector, and a front baffle with a connecting seat compatible with the sampling system's connecting base, along with corresponding ash unloading slide plates and microporous ceramic filter plates. The automated control system consists of a high-voltage power supply, a PLC, wires, an electric actuator, sensors within the flue, and a computer with an automatic resistivity calculation program. Other equipment includes an exhaust pump and a cleaning pump.

[0008] The above-mentioned online resistivity measuring device for fly ash comprises a measuring chamber consisting of a base plate (5) with a sliding groove (17), a top plate (9) with a flushing pipe (19), a tail plate (6) with an exhaust pipe connector (14), and a front baffle (8) with a connecting seat. All measuring chambers are made of stainless steel and are connected by screws. The base plate (5) and top plate (9) have protrusions for installing microporous ceramic filter plates (12). Four electrode modules consisting of stainless steel electrodes (11) and bakelite base plates (10) are installed in the reserved spaces on both sides of the measuring chamber. The sampling head (1) and the three-way sampling pipe (2) are connected to the front baffle (8) of the measuring chamber by screws via a connecting base (3). Dust from the electrostatic precipitator flue enters two measuring chambers through the sampling head (1) and the three-way sampling pipe (2). The measuring chamber tail plate (6) is equipped with an air extraction connector (14), which is connected to an air extraction pump through a hose. The collected flue gas passes through a microporous ceramic filter plate (12) and is discharged by the air extraction pump. The dust is trapped in the measuring chamber, which consists of a bottom plate (5), a top plate (9), and two electrode modules. After the measurement is completed, the ash is discharged. The lower ash discharge slide plate (4) is moved backward by an electric telescopic rod, and the fly ash falls into the flue through the rectangular ash discharge port (16) on the bottom plate (5). The air blown during ash discharge is delivered by an external air pump through a hose to the ash flushing pipe (19) on the top plate (9) and enters the measuring chamber through the ash cleaning hole (20).

[0009] The above-mentioned online resistivity measuring device for fly ash has a base plate (5) with a groove (17) at the bottom to support the ash discharge slide plate (4). The ash discharge slide plate (4) is driven by an electric push rod to slide back and forth to realize the ash discharge operation. The rectangular ash discharge port (16) of the base plate (5) covers the entire bottom of the measuring chamber, which can realize efficient ash discharge. The whole device is placed horizontally in the flue, and the ash discharge port is located at the bottom of the device. Most of the fly ash in the measuring chamber can be discharged by gravity. The remaining small amount of residual fly ash can be removed by blowing through the ash flushing pipe.

[0010] The above-mentioned online resistivity measuring device for fly ash comprises an electrode module consisting of a stainless steel electrode (11) and a bakelite base plate (10). The protruding front end of the stainless steel electrode (11) is inserted into a groove in the bakelite base plate (10), and the rear end is fixed with screws. The bakelite surrounding the stainless steel electrode (11) is of sufficient thickness to meet insulation requirements and is not easily punctured. The four electrode modules are respectively led out to the automation control module by wires.

[0011] The beneficial effects of this invention are that it provides an automated online dust resistivity measuring device that combines an automated control module with the dust resistivity measuring device. This enables the entire measuring device to automate several key processes, including flue gas environment information acquisition and parameter calculation, ash sample collection, data measurement and calculation, result display, and device cleaning. After the main control room issues a sampling command, the entire device automatically executes the process under PLC control, requiring no manual operation. The device's automatic control system can adjust the sampling and cleaning times according to the actual conditions of the flue gas, making it suitable for flue gas with different dust contents. The measured voltage and current data are used to calculate the online dust resistivity through a built-in program and directly transmitted to the main control room host. This allows the main control room to directly adjust the operation of the electrostatic precipitator based on the resistivity changes, effectively improving the dust removal efficiency of the electrostatic precipitator. The automatic ash discharge valve and cleaning nozzle together form the cleaning system, solving the problem of cumbersome ash loading and unloading during the measurement process. The ash inlet of the measuring chamber is located at the top of the front baffle, effectively avoiding the problem of insufficient ash sample accumulation height. The ash discharge port is located at the bottom of the device. During operation, the ash sample is directly discharged back into the electrostatic precipitator flue under gravity, preventing secondary pollution. The design incorporates two measuring chambers, allowing for simultaneous acquisition of two sets of measurement data in a single sampling. The two data transmissions are sent to the control unit for calculation and averaging, significantly improving measurement accuracy. The measuring instrument adopts a modular design, allowing for easy disassembly and assembly of major components, greatly reducing the difficulty of regular instrument maintenance, troubleshooting, and parts replacement. This measuring device is simple in structure and easy to operate, capable of long-term automatic operation within the electrostatic precipitator flue, requiring only 1-2 maintenance checks per year. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is a schematic diagram showing the disassembly of the structure of the present invention;

[0014] Figure 2 This is a schematic diagram of the electrode module and the microporous ceramic.

[0015] Figure 3 This is a schematic diagram of the structure of the tail baffle of the present invention;

[0016] Figure 4 This is a schematic diagram of the structure of the base plate of the present invention;

[0017] Figure 5 This is a schematic diagram of the top plate and the ash-flushing pipe of the present invention;

[0018] Figure 6 This is a schematic diagram of the structure of the front baffle of the component of the present invention;

[0019] Figure 7 This is a schematic diagram of the sampling module connection base structure of the present invention;

[0020] In the diagram: 1-Sampling head, 2-T-way sampling tube, 3-Connecting base, 4-Ash discharge slide plate, 5-Base plate with groove, 6-Tail plate with suction pipe connector, 7-Support column, 8-Front baffle with connecting seat, 9-Top plate with ash flushing pipe, 10-Bakelite base plate, 11-Stainless steel electrode, 12-Microporous ceramic filter plate, 13-Rear baffle, 14-Suction port, 15-Electrode module slot, 16-Rectangular ash discharge port, 17-Groove, 18-Measuring chamber connecting seat, 19-Ash flushing pipe, 20-Ash cleaning air hole, 21-Electrode module and microporous ceramic slot, 22-Connecting seat, 23-Ash flushing interface, 24-Ash inlet trough, 25-Sampling module connecting seat slot, 26-Connecting hole, 27-T-way sampling tube connection port, 28-Measuring chamber ash inlet, 29-Screw placement slot, 30-Top connecting hole, 31-Bottom connecting hole. Detailed Implementation

[0021] When this invention is in operation, the entire working process is divided into three stages: sampling, measurement, and ash removal.

[0022] Preparation before sampling: The sensors installed on the inner wall of the flue start working, collecting parameters such as flue gas volume, flue gas velocity, and flue gas temperature at the sampling point, and transmitting these parameters to the automatic control device, which calculates the sampling time according to the built-in program.

[0023] Sampling Phase: After the control room issues a sampling command, the air pump connected to the tail of the equipment starts working, and the fly ash enters the two measuring chambers through the sampling device. When the preset sampling time is reached, the PLC issues a command according to the program settings, the air pump stops working, and the sampling phase ends.

[0024] Measurement Phase: After the sampling phase, the PLC turns on the measurement power supply according to the preset program, and the measurement data begins to be imported into the main control room computer. Once the voltage rises to the breaking-down dust layer, the high-voltage power supply stops working. The data imported into the main control room computer is automatically exported as a voltage-current relationship curve according to the preset program, and the measurement results are calculated. The data measured in each measurement chamber are calculated and averaged to obtain an accurate specific resistance value, which is then displayed on the screen, ending the measurement phase.

[0025] Ash Removal Stage: After the measurement stage, the PLC issues a command according to the preset program, causing the electric push rod to move the ash removal slide plate at the bottom of the device backward. The ash removal port at the bottom of the measurement chamber opens, and the ash sample falls into the flue under gravity. Then, the cleaning air pump connected to the top ash flushing pipe starts working, blowing air into the sampling chamber to remove residual ash. After the blowing time reaches the set value, the PLC issues a command, the ash removal slide plate moves forward, the ash removal port closes, and the cleaning air pump continues to work for a period of time to remove accumulated ash from the sampling tube. Finally, the PLC issues a command to stop the cleaning air pump, ending the ash removal stage.

[0026] The entire measurement process of this invention is automatically controlled by the control unit, requiring no manual operation.

[0027] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An online automatic measuring device for dust resistivity, characterized in that, include: (a) Sampling system: consisting of a sampling head (1), a three-way sampling tube (2), and a connecting base (3), wherein the outlet end of the three-way sampling tube (2) is symmetrically bifurcated to form a dual channel; (b) Integrated ash removal and cleaning system: including two measuring chambers, each measuring chamber is welded together by a bottom plate (5) with a chute, a top plate (9) with a punching ash pipe (19), a tail plate (6) with an exhaust pipe connector (14), and a front baffle (8) with a connecting seat. A rectangular ash discharge port (16) is provided in the middle of the base plate (5), and a groove (17) matching the ash discharge slide plate (4) is provided at the bottom of the base plate (5); The top plate (9) is provided with a dust removal air hole (20), which faces the measuring chamber. The tail end of the dust flushing pipe (19) is connected to a dust removal air pump. (c) Electrode system: It consists of four independent electrode modules forming two groups. Each module is formed by the protruding part of the front end of the stainless steel electrode (11) being inserted into the groove of the bakelite base plate (10). The four modules are placed on both sides of the double measuring chamber and fixed by the slot (15). (d) Automated control system: including PLC, high voltage power supply, electric actuator, sensor in flue and computer with resistivity calculation program; After the control room issues a sampling command, the air pump connected to the tail of the equipment starts to work. Fly ash enters the two measuring chambers through the three-way sampling pipe (2). The PLC issues a command according to the preset program, and the electric push rod drives the ash discharge slide plate at the bottom of the device to move backward. The ash discharge port at the bottom of the measuring chamber opens, and the ash sample falls into the flue under the action of gravity. Then, the ash cleaning air pump connected to the top flushing ash pipe starts to work and blows air into the sampling chamber to remove the residual ash sample. After the blowing time reaches the set value, the PLC issues a command, the ash discharge slide plate moves forward, and the ash discharge port closes.

2. The apparatus according to claim 1, characterized in that, The thickness of the bakelite base plate (10) meets the insulation requirements and is not easily penetrated. The protruding part of the front end of the stainless steel electrode (11) is inserted into the groove in the bakelite base plate (10), and the rear part is fixed with screws.

3. The apparatus according to claim 1, characterized in that, The rectangular ash discharge port (16) is located at the bottom of the measuring chamber, which can realize efficient ash discharge. The ash discharge slide plate (4) is driven by an electric push rod to slide back and forth to realize the ash discharge operation.

4. The apparatus according to claim 1, characterized in that, The four stainless steel electrodes are identical in size and their centers are on the same horizontal line. The two measuring chambers are connected by screws, which can obtain two sets of data in one measurement. The data are calculated by PLC and the average value is taken to obtain an accurate specific resistance value.

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