A chopping pulse power supply dust removal system and method

Abstract

The present invention discloses a chopping pulse power supply dust removal system and method, which belongs to the technical field of electrostatic precipitator, and includes a signal processor, a switch synchronization signal generating circuit, a multi-channel synchronization signal generating circuit, a synchronization signal amplifying circuit, a state parameter detection circuit, a series switch component, a bias circuit, and a dust concentration and flow detection sensor. The present invention adopts a series switch component and a bias circuit for use, which can generate a DC bias voltage and a pulse voltage at the same time. At the same time, combined with database query and detection technology, the frequency and pulse width of the DC bias voltage and the pulse voltage can be changed in time according to the concentration and flow of gas dust on site, and high specific resistance and low specific resistance dust, mist and ordinary dust can be adsorbed at the same time, achieving the best dust removal efficiency, and is worthy of being promoted and used.

Description

Technical Field

[0001] The invention relates to the technical field of electric dust collectors, and in particular to a chopping-type pulse power supply dust removal system and method. Background Art

[0002] In the operation of catering, coal-fired heating equipment, and industrial production equipment such as metallurgy and mining, it is necessary to discharge the exhaust gas containing dust, smoke and atomized oil droplets. In order to reduce pollution, they must be effectively removed before discharge. The resistivity (resistance per unit volume) of dust and atomized oil droplets in the exhaust gas can be divided into low resistivity and high resistivity. Low resistivity has high conductivity and is easy to release charge at the anode (dust collecting electrode), but the characteristics of high resistivity dust are the opposite. Therefore, driven by the electric field force, when the first layer of high resistivity dust and atomized oil droplets reaches the anode (dust collecting electrode), they have not yet released their charges. The next layer of high resistivity dust and atomized oil droplets are difficult to reach the dust collecting electrode and release their charges due to the obstruction of the first layer to the dust collecting electrode, forming the surface potential of the dust layer and the atomized oil droplets. An additional reverse electric field of the dust layer will appear in the corona electric field of the dust collector. This reverse electric field will weaken or even shield the corona electric field of the dust collector. This is called the back corona effect. The back corona effect reduces the efficiency of the dust collector and even causes failure and damage to the dust collector.

[0003] The conventional DC high voltage powered electrostatic precipitator adopts a continuous (DC) power supply mode. In the presence of high resistivity dust and atomized oil droplets, the efficiency of the precipitator is reduced due to the back corona phenomenon. Therefore, a chopper pulse power supply precipitator system is proposed. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to overcome the shortcomings of a fully DC-powered electrostatic precipitator, which has a poor adsorption effect on high-resistance dust and mist and is prone to back corona effect, and a pulse power supply method, in which low-resistance dust cannot be charged and is prone to directly escape from the electrostatic precipitator during power supply interruptions. A chopper-type pulse-powered dust removal system is provided. This system superimposes a pulse with adjustable frequency and pulse width on the original high-voltage DC, which can take both into account. It is suitable for catering, coal-based heating equipment, metallurgy, mineral processing and other fields with small dust and exhaust gas emissions (for example, less than 100,000 cubic meters per hour).

[0005] The present invention solves the above technical problems through the following technical solutions: a signal processor, a switch synchronization signal generating circuit, a multi-channel synchronization signal generating circuit, a synchronization signal amplifying circuit, a state parameter detection circuit, a series switch component, a bias circuit, and a dust concentration and flow detection sensor; the signal processor, the switch synchronization signal generating circuit, the multi-channel synchronization signal generating circuit, and the synchronization signal amplifying circuit are electrically connected in sequence, an input end of the state parameter detection circuit is electrically connected to the dust concentration and flow detection sensor, and the other end is connected to the signal processor, the series switch component includes a plurality of switches connected in series, the bias circuit includes a plurality of bias resistors, and the plurality of bias resistors are respectively connected in parallel at both ends of each switch, after the bias circuit is connected to the series switch component, one end is electrically connected to the cathode of the electrostatic precipitator, and the other end is electrically connected to the original high-voltage DC power supply of the electrostatic precipitator, the dust concentration and flow detection sensor is arranged at the dust gas discharge port of the electrostatic precipitator, and the synchronization signal amplifying circuit is electrically connected to each switch.

[0006] Furthermore, the chopper-type pulse-powered dust removal system also includes a current and voltage measurement circuit, one end of which is electrically connected to the signal processor, and the other end of which is electrically connected to the series switch component and the bias circuit.

[0007] Furthermore, the chopper-type pulse-powered dust removal system also includes an LCD display circuit, and the LCD display circuit is electrically connected to the signal processor.

[0008] Furthermore, the chopper-type pulse-powered dust removal system also includes a database, which is electrically connected to the signal processor.

[0009] The present invention also provides a chopper pulse power supply dust removal method, which uses the above system to achieve dust removal and demisting of an electrostatic precipitator, including the following steps:

[0010] S1: The series switch component and the plurality of bias resistors are synchronously turned on and off under the action of a synchronous trigger signal, thereby generating a pulse with a DC bias voltage at the cathode of the electrostatic precipitator;

[0011] S2: The pulse with DC bias generates a corona electric field between the cathode and anode plates of the dust collector and ionizes the air to generate corona plasma. The negative ions in the corona plasma are adsorbed by the dust or atomized droplets, causing the dust or atomized droplets to carry a negative charge.

[0012] S3: Negatively charged dust or atomized droplets move toward the anode plate under the driving force of the electric field, gather on the anode plate, release negative charges, and achieve dust removal.

[0013] Furthermore, in step S1, the frequency and width of the pulse are synchronous trigger signals of optimal pulse frequency and pulse width obtained after the signal processor processes the dust concentration and gas flow data obtained by the state parameter detection circuit, the dust concentration and flow detection sensor.

[0014] Furthermore, the specific process of obtaining the synchronous trigger signal of the optimal pulse frequency and pulse width is as follows:

[0015] S11: Detect dust concentration and gas flow rate through a state parameter detection circuit to obtain detection results of dust concentration and gas flow rate;

[0016] S12: querying a database according to the obtained dust concentration and gas flow rate detection results to determine whether the dust concentration and gas flow rate values ​​exist in the database;

[0017] S13: If it exists, the optimal pulse frequency and pulse width corresponding to the dust concentration and gas flow rate values ​​are obtained; if it does not exist, the optimal pulse frequency and optimal pulse width are calculated according to the dust concentration and gas flow rate values, and a new record is inserted into the database;

[0018] S14: Use a signal processor to control the output of the optimal pulse frequency and optimal pulse width obtained in step S13.

[0019] Furthermore, in the step S12, the database stores a mapping relationship between dust concentration, gas flow rate value, optimal pulse frequency, and optimal pulse width.

[0020] Compared with the prior art, the present invention has the following advantages: the chopper-type pulse-powered dust removal system adopts a series switch component and a bias circuit to simultaneously generate a DC bias voltage and a pulse voltage. Combined with database query and detection technology, the frequency and pulse width of the DC bias voltage and the pulse voltage can be changed in time according to the concentration and flow of gas dust on site. It can simultaneously adsorb high-resistance and low-resistance dust, mist and ordinary dust to achieve the best dust removal efficiency, and is worthy of being promoted and used. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a chopper pulse power supply dust removal system in an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of a bias circuit in an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the structure of the control host in an embodiment of the present invention;

[0024] Figure 4This is a pulse high voltage output simulation diagram in an embodiment of the present invention;

[0025] Figure 5 : is a circuit schematic diagram of a chopper-type pulse power supply dust removal system in an embodiment of the present invention;

[0026] Figure 6 is a control flow chart of a chopper-type pulse power supply dust removal system in an embodiment of the present invention;

[0027] Figure 7 It is a schematic diagram of a database query flow in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0029] like Figure 1 , 2 As shown, this embodiment provides a technical solution: a chopper pulse power supply dust removal system, including a control host, a modular series switch component, a bias circuit (multiple bias resistors), a dust concentration and flow detection sensor, and a current and voltage measurement circuit, wherein the series switch component is electrically connected to the control host, the dust concentration and flow detection sensor is installed at the position of the dust gas discharge port of the electrostatic precipitator and is connected to the control host signal input port, one end of the current and voltage measurement circuit is electrically connected to the series switch component, and the other end is electrically connected to the control host, the module composed of the series switch component and the bias circuit is connected to the original electrostatic precipitator cathode (corona electrode) power supply circuit, the series switch component includes multiple switches in series (such as IGBT), and multiple bias resistors are respectively connected in parallel at both ends of each switch. The present invention uses the series switch component and the bias circuit to generate a pulse voltage with a DC bias at the cathode of the electrostatic precipitator, which can simultaneously adsorb high specific resistance and low specific resistance dust, mist and ordinary dust to achieve the best dust removal efficiency.

[0030] like Figure 3 As shown, in this embodiment, the control host includes a signal processor (CPU, such as a single chip microcomputer), a switch synchronization signal generating circuit, a multi-channel synchronization signal generating circuit, a synchronization signal amplifying circuit, a state parameter detection circuit, an LCD display circuit, a database, etc. The signal processor, the switch synchronization signal generating circuit, the multi-channel synchronization signal generating circuit, the synchronization signal amplifying circuit, and the series switch component are electrically connected in sequence, the input end of the state parameter detection circuit is electrically connected to the dust concentration and flow detection sensor, and the other end is connected to the signal processor, and the LCD display circuit is electrically connected to the signal processor;

[0031] Specifically, the functions of each component in the control host are as follows:

[0032] LCD display circuit: can timely display the parameters of on-site voltage, current, dust concentration and flow rate detection, and has alarm signals such as overvoltage and overcurrent, and can set manual and automatic adjustment functions; state parameter detection circuit: detect whether the dust concentration and flow rate meet the requirements; dust concentration and flow rate sensor: output the detected concentration and flow rate information in the form of electrical signals. Switch synchronization signal generation circuit: synchronously turn on or off the signal; multi-channel synchronization signal generation circuit: generate signals of several channels; synchronization signal amplification circuit: amplify the original signal and output it; series switch component and bias circuit: the module composed of the series switch component and the bias circuit, under the action of the synchronous drive signal, synchronously turns on and off the switch, thereby outputting DC bias and pulse voltage to the cathode of the electrostatic precipitator.

[0033] In this embodiment, the module consisting of the series switch component and the bias circuit opens and closes the switch synchronously under the action of the synchronous drive signal, thereby outputting a DC bias voltage and a pulse voltage to the cathode of the electrostatic precipitator.

[0034] In this embodiment, the bias resistor of the bias circuit can generate a DC bias voltage when the switch is disconnected, and can also provide an automatic voltage balancing function to ensure that the operating voltages of the series switches are consistent.

[0035] In this embodiment, the database includes a database storage and call module, which, combined with gas and dust concentration and flow detection technology, can change the pulse frequency and pulse width in time according to the concentration and flow of gas and dust on site, and can also supplement the database with new working condition data as needed.

[0036] like Figure 4 As shown, the series switch component and multiple bias resistors are synchronously turned on and off under the action of the synchronous trigger signal, thereby generating a pulse with a DC bias voltage at the cathode of the electrostatic precipitator. The frequency and width of the pulse depend on the dust concentration, gas flow rate and other parameters input by the state parameter detection circuit. After being processed by the signal processor (CPU) and combined with the database, the synchronous trigger signal of the optimal pulse frequency and pulse width suitable for the current dust concentration and gas flow rate is output, as shown in FIG. Figure 6 The control flow chart is shown.

[0037] Specifically, the sampled current and voltage data are returned to the control host through the sensor for data identification. According to the voltage and current range designed by this design scheme, it is judged whether it exceeds the limit, and then whether the data is appropriate; if it does not exceed the limit, the data can be processed; if it exceeds the limit, re-sampling is required.

[0038] The pulse with DC bias generates a corona electric field between the cathode (corona electrode) and anode (dust collecting electrode) plates of the dust collector and ionizes the air to generate corona plasma. The negative ions (mainly electrons) in the corona plasma are adsorbed by the dust or atomized droplets, making the dust or atomized droplets negatively charged. The negatively charged dust or atomized droplets move toward the anode (dust collecting electrode) plate under the driving force of the electric field, gather on the anode plate, and release the negative charge. Since the electric field is generated by a high voltage with DC bias and pulses, the charged high resistivity ordinary dust or atomized droplets can fully release the adsorbed charge.

[0039] It should be noted that: Figure 5 The function of high-frequency and high-voltage isolation pulse transformer is to provide the control voltage of the synchronous signal. The frequency of the signal emitted by the high-frequency and high-voltage pulse transformer is generally between 10KHZ and 100KHZ, which is much higher than the frequency of the signal emitted by the ordinary transformer. The working principle of the high-frequency and high-voltage pulse transformer is that the pulse transformer converts the sinusoidal voltage transmitted by the power supply into a narrow pulse output voltage by utilizing the magnetic saturation of the iron core.

[0040] like Figure 7 As shown, the specific process of the dust concentration and gas flow parameters being processed by the signal processor (CPU) and combined with the database to output the synchronous trigger signal of the optimal pulse frequency and optimal pulse width suitable for the current dust concentration and gas flow is as follows:

[0041] S101: Detect dust concentration and gas flow rate through a state parameter detection circuit to obtain detection results of dust concentration and gas flow rate;

[0042] S102: querying a database according to the obtained dust concentration and gas flow rate detection results to determine whether the dust concentration and gas flow rate values ​​exist in the database;

[0043] S103: If it exists, the optimal pulse frequency and pulse width corresponding to the dust concentration and gas flow rate values ​​are obtained; if it does not exist, the optimal pulse frequency and optimal pulse width are calculated according to the dust concentration and gas flow rate values ​​by using an algorithm, and a new record is inserted into the database at the same time;

[0044] S104: Use a signal processor to control and output the optimal pulse frequency and pulse width obtained in step S103.

[0045] In this embodiment, in step S102, the database stores a mapping relationship between dust concentration, gas flow rate value, and optimal pulse frequency and pulse width.

[0046] In this embodiment, in step S103, the specific calculation process of the algorithm is as follows:

[0047] 1. Use dust concentration to find the optimal pulse frequency:

[0048] Dust charge decay formula:

[0049]

[0050] Where Q is the output charge; Q 0 is the input charge; ρ t is the dust specific resistance; ε 0 is the dielectric constant of vacuum; ε p is the relative dielectric constant of the medium; T is the effective value time of the unit pulse;

[0051] Experiments show that when the ratio of the output charge to the input charge When the dust concentration is , it can be considered that the result meets the dust removal requirements. The relationship between dust concentration and charge is:

[0052]

[0053] Where N is the output dust concentration, N 0 is the input dust concentration. The ratio of input dust concentration to output dust concentration is equal to the ratio of output dust charge to input dust charge, so the input and output dust concentrations can be substituted into the dust charge decay formula to obtain the effective value time T of the unit pulse.

[0054] According to the relationship between unit pulse effective value time T and frequency f:

[0055]

[0056] Where D is the duty cycle of the PWM pulse. Substituting T obtained from the dust charge decay formula into the above formula can obtain the optimal pulse frequency f.

[0057] 2. Use gas flow rate to find the optimal pulse width:

[0058]

[0059] Among them, ε 0 is the dielectric constant of vacuum; ε p is the relative dielectric constant of the medium; N is the concentration; d p is the particle size; E c is the plate field strength (i.e. pulse width); u is the medium viscosity coefficient;

[0060] According to Deutsch's formula:

[0061] Where, η is efficiency; A is cross-sectional area; Q is flow rate;

[0062] When the flow rate increases, the dust removal efficiency decreases. To ensure that the efficiency remains unchanged, it is necessary to modify E c The plate field strength (i.e. pulse width) is adjusted to achieve the optimal pulse width m.

[0063] In summary, the chopper-type pulse-powered dust removal system of the above-mentioned embodiment directly connects the cathode (corona electrode) of the high-voltage DC power supply to the middle of the series switch assembly and the bias circuit; by controlling the frequency and time of the synchronous opening and closing of the switch of the series switch assembly, a pulse with adjustable frequency and pulse width superimposed on the basis of DC bias can be obtained on the cathode (corona electrode) of the electrostatic precipitator--DC high voltage, and pulse--DC high voltage is generated between the cathode (corona electrode) and the anode (dust collecting electrode) by pulse--DC high voltage, and the air is ionized to produce corona plasma, and dust and various atomized gases are negatively charged due to the adsorption of electrons in the corona electric field, and move to the positive electrode (dust collecting electrode) under the action of the electric field, and release electrons when different resistivity dust and various atomized gases move to the anode (dust collecting electrode) and are adsorbed by the anode, thereby achieving the purpose of dust removal and demisting, which is worthy of being promoted and used.

[0064] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A chopper pulse power supply dust removal system, characterized in that: include: Electrostatic precipitator, signal processor, switch synchronization signal generating circuit, multi-channel synchronization signal generating circuit, synchronization signal amplifying circuit, state parameter detection circuit, series switch component, bias circuit, dust concentration and flow detection sensor; the signal processor, the switch synchronization signal generating circuit, the multi-channel synchronization signal generating circuit, and the synchronization signal amplifying circuit are electrically connected in sequence, the input end of the state parameter detection circuit is electrically connected to the dust concentration and flow detection sensor, and the other end is connected to the signal processor, the series switch component includes a plurality of switches connected in series, the bias circuit includes a plurality of bias resistors, and the plurality of bias resistors are respectively connected in parallel at both ends of each switch, after the bias circuit is connected to the series switch component, one end is electrically connected to the cathode of the electrostatic precipitator, and the other end is electrically connected to the original high-voltage DC power supply of the electrostatic precipitator, the dust concentration and flow detection sensor is arranged at the dust gas outlet of the electrostatic precipitator, and the synchronization signal amplifying circuit is electrically connected to each switch.

2. A chopper-type pulse power supply dust removal system according to claim 1, characterized in that: The chopper-type pulse-powered dust removal system also includes a current and voltage measurement circuit, one end of which is electrically connected to the signal processor, and the other end of which is electrically connected to the series switch component and the bias circuit.

3. A chopper-type pulse power supply dust removal system according to claim 2, characterized in that: The chopper-type pulse-powered dust removal system also includes an LCD display circuit, which is electrically connected to the signal processor.

4. A chopper-type pulse power supply dust removal system according to claim 3, characterized in that: The chopper-type pulse-powered dust removal system also includes a database, which is electrically connected to the signal processor.

5. A chopper pulse power supply dust removal method, using the system as claimed in any one of claims 1 to 4 to achieve dust removal and demisting of an electrostatic precipitator, characterized in that: The following steps are involved: S1: The series switch component and the plurality of bias resistors are synchronously turned on and off under the action of a synchronous trigger signal, thereby generating a pulse with a DC bias voltage at the cathode of the electrostatic precipitator; S2: The pulse with DC bias generates a corona electric field between the cathode and anode plates of the dust collector and ionizes the air to generate corona plasma. The negative ions in the corona plasma are adsorbed by the dust or atomized droplets, causing the dust or atomized droplets to carry a negative charge. S3: Negatively charged dust or atomized droplets move toward the anode plate under the driving force of the electric field, gather on the anode plate, release negative charges, and achieve dust removal.

6. A chopper-type pulse power supply dust removal method according to claim 5, characterized in that: In step S1, the frequency and width of the pulse are synchronous trigger signals of the optimal pulse frequency and pulse width obtained after the signal processor processes the dust concentration and gas flow data obtained by the state parameter detection circuit, the dust concentration and flow detection sensor.

7. A chopper-type pulse power supply dust removal method according to claim 6, characterized in that: The specific process of obtaining the synchronous trigger signal of the optimal pulse frequency and pulse width is as follows: S11: Detect dust concentration and gas flow rate through a state parameter detection circuit to obtain detection results of dust concentration and gas flow rate; S12: querying a database according to the obtained dust concentration and gas flow rate detection results to determine whether the dust concentration and gas flow rate values ​​exist in the database; S13: If it exists, the optimal pulse frequency and pulse width corresponding to the dust concentration and gas flow rate values ​​are obtained; if it does not exist, the optimal pulse frequency and optimal pulse width are calculated according to the dust concentration and gas flow rate values, and a new record is inserted into the database; S14: Use a signal processor to control the output of the optimal pulse frequency and optimal pulse width obtained in step S13.

8. A chopper-type pulse power supply dust removal method according to claim 7, characterized in that: In the step S12, the database stores a mapping relationship between dust concentration, gas flow rate value, optimal pulse frequency, and optimal pulse width.

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