A microwave measurement system for coal powder concentration in power station boilers

Abstract

The invention relates to the field of coal power technology, in particular to a microwave measurement system for coal powder concentration of a power station boiler, comprising an airflow pipe, the front of the airflow pipe is connected with a detection pipe, the detection pipe adopts a π-type design, and electric butterfly valves are arranged at both ends and both sides of the outer side, and a microwave measuring device is arranged in the middle of the outer side of the detection pipe; the microwave measuring device comprises a microwave oscillator, a directional coupler, an isolator, a detector, a DC transmitter, a data acquisition unit, a variable attenuator, a transmitting antenna, a receiving antenna, and a main controller; the invention solves the problem that the existing microwave detection device for coal powder concentration of power station boilers is mostly integrated on the inner wall of the airflow channel, and the detection error is easily caused by the accumulation of coal powder in the detection pipe during the detection process, resulting in low detection efficiency, thereby making it difficult to rationally control the combustion of the boiler, and the integrated fixed design is not conducive to maintenance and repair.

Description

Technical Field

[0001] The invention relates to the technical field of coal power generation, and in particular to a microwave measurement system for coal powder concentration of a power station boiler. Background Art

[0002] The concentration of pulverized coal in fly ash of power station boiler is an important technical indicator of the combustion efficiency and operation economy of coal-fired boilers in thermal power plants. Since the main component of pulverized coal is carbon, the concentration of pulverized coal can be measured by detecting the carbon content in fly ash. As our country's power generation units continue to develop towards commercial parameters and large capacity, real-time online detection of pulverized coal concentration in fly ash of power station boilers has become increasingly important and cutting in order to control and optimize boiler combustion efficiency, reduce coal consumption in power generation, and improve the comprehensive utilization efficiency of pulverized coal. Real-time detection of pulverized coal concentration in fly ash will help staff to adjust boiler combustion and pulverizing systems in a timely manner, improve boiler combustion efficiency and control level, and also reduce incomplete combustion of coal in power station boiler operation as much as possible, reduce carbon content in fly ash, improve effective utilization of coal, and reduce environmental pollution.

[0003] There are many existing methods for detecting the pulverized coal concentration in power station boilers, such as fluidized bed CO2 measurement method, optical combustion method, weight combustion method, infrared measurement method, radiation method, microwave absorption method, microwave resonance method and traditional burn-off method. Among them, the microwave absorption method is widely used due to its fast detection speed and high safety. The existing microwave detection devices for pulverized coal concentration in power station boilers are mostly integrated on the inner wall of the air flow channel. During the detection process, it is easy to cause detection errors due to the accumulation of pulverized coal in the detection tube, resulting in low detection efficiency, making it difficult to rationally control the boiler combustion, and the integrated fixed design is not conducive to maintenance and repair. Summary of the invention

[0004] The object of the present invention is to provide a microwave measurement system for coal powder concentration in a power station boiler to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A microwave measurement system for coal powder concentration of a power station boiler, comprising an airflow pipe, the front of which is connected to a detection pipe, the detection pipe adopts a π-shaped design, and electric butterfly valves are arranged at both ends and both sides of the outer side, and a microwave measurement device is arranged in the middle of the outer side of the detection pipe;

[0007] The microwave measuring device comprises a microwave oscillator, a directional coupler, an isolator, a detector, a DC transmitter, a data acquisition unit, a variable attenuator, a transmitting antenna, a receiving antenna and a main controller;

[0008] The microwave oscillator, directional coupler, isolator, detector, DC transmitter, data acquisition unit, variable attenuator and transmitting antenna form a microwave transmitting part. The microwave oscillator generates a microwave signal which is input, output and isolated and screened by the isolator. The variable attenuator is used to attenuate and debug the screened ultrasonic signal. The directional coupler is used to divide and distribute the signal. One signal is formed into a reference monitoring signal through the detector, and the other signal is formed into an actual detection signal through the transmitting antenna, thereby completing the microwave signal transmission.

[0009] The detector, DC transmitter, data acquisition unit, receiving antenna and main controller constitute a microwave receiving part, the detector detects the signal received by the receiving antenna and the reference monitoring signal, the DC transmitter amplifies the two signals, and then collects and summarizes them to the main controller through the data acquisition unit, so as to complete the reception of the microwave signal emitted by the microwave emitting part;

[0010] The transmitting antenna and the receiving antenna are symmetrically fixed on the upper and lower sides of the detection tube, and the fixed inclination angle between them is 20-30 degrees.

[0011] Preferably, both ends of the outer side of the detection tube are provided with air outlets, and the outer ends of the air outlets are connected to a high-pressure blower through a connecting pipeline.

[0012] Preferably, the microwave oscillator is a microwave crystal oscillator.

[0013] Preferably, the directional coupler is a waveguide cross directional coupler.

[0014] Preferably, the isolator is a linear optocoupler isolator.

[0015] Preferably, the detector is a synchronous detector.

[0016] Preferably, the data acquisition unit has a built-in single-chip microcomputer using an AT89C52 single-chip microcomputer.

[0017] Preferably, the detection tube is fixedly connected to the airflow tube via a flange, and sealing gaskets are provided at the connections.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0019] In the present invention, the external detection tube design is convenient for installation and is conducive to later maintenance. The π-shaped detection tube, in conjunction with the air outlet and the butterfly valve, can realize the free on-off control of the detection tube and the airflow tube and the cleaning of the inner wall of the detection tube. During detection, the inner wall of the detection tube can be cleaned first, and then the coal powder concentration in the fly ash can be detected in conjunction with the microwave measuring device. This method can avoid the accumulation of coal powder in the detection tube and affect the detection accuracy, and its detection accuracy is high. At the same time, the transmitting antenna and the receiving antenna in the microwave measuring device are symmetrically staggered. The staggered angle is 20-30°, which can effectively avoid the reflection of microwave signals in the detection tube, avoid oscillation, and will not affect the transmission of microwave signals, thereby further improving the detection accuracy, so that the rational control of boiler combustion can be well met. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0021] Figure 2 This is a diagram of the antenna installation position of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0022] Figure 3 This is a measurement principle block diagram of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0023] Figure 4 This is a principle block diagram of the transmitting part of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0024] Figure 5 This is a principle block diagram of the receiving part of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0025] Figure 6 This is a directional coupling principle diagram of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0026] Figure 7 This is a microwave oscillator equipment parameter diagram of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0027] Figure 8 This is a parameter diagram of a directional coupler device of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0028] Fig. 9 This is a parameter diagram of an isolator device of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0029] Fig.10 A detection wave equipment parameter diagram of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0030] Fig.11This is a parameter diagram of a DC transmitter device of a microwave measurement system for coal powder concentration in a power station boiler according to the present invention;

[0031] Fig.12 This is a parameter diagram of a variable attenuator device in a microwave measurement system for coal powder concentration in a power station boiler according to the present invention.

[0032] Description of reference numerals:

[0033] 1. Air flow pipe; 2. Detection tube; 3. Electric butterfly valve; 4. Microwave measuring device; 401. Microwave oscillator; 402. Directional coupler; 403. Isolator; 404. Detector; 405. DC transmitter; 406. Data acquisition unit; 407. Variable attenuator; 408. Transmitting antenna; 409. Receiving antenna; 410. Main controller; 5. Air outlet. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] See also Figure 1-12 , the present invention provides a technical solution:

[0039] A microwave measurement system for coal powder concentration in a power station boiler, see 1, comprises an airflow pipe 1, the front of which is connected to a detection pipe 2, the detection pipe 2 adopts a π-type design, and electric butterfly valves 3 are arranged at both ends and both sides of the outer side, so as to facilitate the on-off control of the detection pipe and the inside of the airflow pipe; a microwave measuring device 4 is arranged in the middle of the outer side of the detection pipe 2, and the detection pipe is designed as a separate external connection, so that the detection parameters are highly consistent, and there is no need to calibrate the parameters of each pipe separately due to different airflow pipe diameters, the operation difficulty is low, and the external connection design is convenient for disassembly and assembly, which is helpful for later maintenance and repair.

[0040] Please refer to 3. The microwave measuring device 4 includes a microwave oscillator 401, a directional coupler 402, an isolator 403, a detector 404, a DC transmitter 405, and its equipment parameters are shown in Fig.11 ; Data acquisition unit 406, variable attenuator 407, its equipment parameters see Fig.12 ; The transmitting antenna 408, the receiving antenna 409, and the main controller 410 realize the transmission and reception of microwave signals, and utilize the characteristic that the carbon particles in the coal powder have strong absorption of electromagnetic waves, and then detect the attenuation of its microwave transmission and reception signals, so as to detect the coal powder concentration in the fly ash, and utilize a directional coupler to first separate a part of the microwave energy from the microwave signal emitted by the microwave oscillator before entering the transmitting antenna as a reference signal, and transmit it to the main controller as a monitoring signal after detection and amplification, and the other microwave signals pass through the transmitting antenna through the fly ash in the detection tube to reach the receiving antenna, and are transmitted to the main controller as a measurement signal after detection and amplification, and then the main controller corrects the measurement signal according to the waveguide condition of the monitoring signal, thereby improving the measurement accuracy.

[0041] Please refer to 4. The microwave oscillator (401), directional coupler (402), isolator (403), detector (404), DC transmitter (405), data acquisition unit (406), variable attenuator (407) and transmitting antenna (408) constitute a microwave transmitting part. The microwave signal generated by the microwave oscillator (401) is input, output and isolated and screened by the isolator (403). The screened ultrasonic signal is attenuated and adjusted by the variable attenuator (407). Then, the signal is divided and split by the directional coupler (402). One signal is formed into a reference monitoring signal by the detector (404), and the other signal is formed into an actual detection signal by the transmitting antenna (408), thereby completing the microwave signal transmission.

[0042] Please refer to 5. The detector (404), DC transmitter (405), data acquisition unit (406), receiving antenna (409) and main controller (410) constitute a microwave receiving part. The detector (404) detects the signal received by the receiving antenna (409) and the reference monitoring signal. The DC transmitter (405) amplifies the two signals, and then collects and summarizes them to the main controller (410) through the data acquisition unit (406), thereby completing the reception of the microwave signal emitted by the microwave emitting part.

[0043] Please refer to 2, the transmitting antenna 408 and the receiving antenna 409 are symmetrically fixed on the upper and lower sides of the detection tube 2, and the fixed inclination angle between them is 20-30 degrees, which can effectively avoid the microwave signal from being reflected in the detection tube and oscillation, and will not affect the microwave signal transmission, thereby further improving the detection accuracy.

[0044] In the present embodiment, please refer to 1, air outlets 5 are provided at both ends of the outer side of the detection tube 2, and the outer ends of the air outlets 5 are connected to a high-pressure air blower through a connecting pipeline. The external high-pressure air blower is used in conjunction with the internal electric butterfly valve to realize self-cleaning of the inner wall of the detection tube. During cleaning, the butterfly valves on both sides of the detection tube and the butterfly valves at the air outlets on both sides are staggered on and off to control opening. When the butterfly valve on one side is opened, the butterfly valve on the diagonal air outlet is opened, and vice versa, so as to achieve alternating blowing of external high-pressure air blowers at the double air outlets to ensure the self-cleaning efficiency inside the detection tube.

[0045] In this embodiment, the microwave oscillator 401 adopts a microwave crystal oscillator to ensure good oscillator stability and high output power. The device parameters are shown in Figure 7 .

[0046] In this embodiment, refer to 6, the directional coupler 402 adopts a waveguide cross directional coupler, so that when the signal is input from port 1, the small hole is on the right side of the signal propagation direction, it can be inferred that there is no signal output from port 4 and there is a signal output from port 3, thereby realizing directional coupling. The device parameters are shown in Figure 8 .

[0047] In this embodiment, the isolator 403 uses a linear optical coupler isolator to convert the input signal and output it, thereby improving the signal stability and making the measurement more accurate and reliable. Fig. 9 .

[0048] In this embodiment, the detector 404 adopts a synchronous detector with a frequency bandwidth of 8.2 GHz-12 GHz; it is used for modulation of single sideband amplitude modulation signals or modulation of residual sideband amplitude modulation signals. The device parameters are shown in Fig.10 .

[0049] In this embodiment, the built-in single-chip microcomputer of the data acquisition unit 406 adopts the AT89C52 single-chip microcomputer to achieve low voltage and high performance control.

[0050] In this embodiment, the detection tube 2 is fixedly connected to the airflow tube 1 through a flange, and sealing gaskets are provided at the connection points to facilitate the disassembly and assembly of the detection tube.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microwave measurement system for coal powder concentration in power station boilers, characterized in that: The invention comprises an airflow pipe (1), the front side of the airflow pipe (1) is connected to a detection pipe (2), the detection pipe (2) adopts a π-shaped design, and electric butterfly valves (3) are arranged at both ends and both sides of the outer side, and a microwave measuring device (4) is arranged in the middle of the outer side of the detection pipe (2); The microwave measuring device (4) comprises a microwave oscillator (401), a directional coupler (402), an isolator (403), a detector (404), a DC transmitter (405), a data acquisition unit (406), a variable attenuator (407), a transmitting antenna (408), a receiving antenna (409) and a main controller (410); The microwave oscillator (401), directional coupler (402), isolator (403), detector (404), DC transmitter (405), data acquisition unit (406), variable attenuator (407) and transmitting antenna (408) constitute a microwave transmitting part. The microwave oscillator (401) generates a microwave signal, which is input and output through the isolator (403) and isolated and screened for power supply signal. The screened ultrasonic signal is attenuated and adjusted through the variable attenuator (407). The signal is then divided and split through the directional coupler (402). One signal is formed into a reference monitoring signal through the detector (404), and the other signal is formed into an actual detection signal through the transmitting antenna (408), thereby completing the microwave signal transmission. The detector (404), the DC transmitter (405), the data acquisition unit (406), the receiving antenna (409) and the main controller (410) constitute a microwave receiving part, wherein the detector (404) performs detection on the signal received by the receiving antenna (409) and the reference monitoring signal detection, and the DC transmitter (405) amplifies the two signals, and then collects and aggregates them to the main controller (410) through the data acquisition unit (406), thereby completing the reception of the microwave signal emitted by the microwave emitting part; The transmitting antenna (408) and the receiving antenna (409) are symmetrically fixed on the upper and lower sides of the detection tube (2), and the fixed inclination angle between them is 20-30 degrees.

2. A microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: Both ends of the outer side of the detection tube (2) are provided with air outlets (5), and the outer ends of the air outlets (5) are connected to a high-pressure air blower via a connecting pipeline.

3. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The microwave oscillator (401) is a microwave crystal oscillator.

4. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The directional coupler (402) is a waveguide cross directional coupler.

5. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The isolator (403) is a linear optocoupler isolator.

6. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The detector (404) is a synchronous detector.

7. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The data acquisition unit (406) has a built-in single-chip microcomputer which is an AT89C52 single-chip microcomputer.

8. The microwave measurement system for coal powder concentration of a power plant boiler according to claim 1, characterized in that: The detection tube (2) is fixedly connected to the airflow tube (1) via a flange, and sealing gaskets are provided at the connection points.

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