An on-line measurement optical element protection device and method for pulverized coal fineness in a power plant

Abstract

The present invention discloses an optical element protection device and method for on-line measurement of pulverized coal fineness in a power plant, which relates to the field of pulverized coal fineness detection in a power plant. The protection device mainly includes a measurement channel, an optical channel, a light source, a signal receiving lens, and an optical window. A first air blowing system and a second air blowing system are arranged outside the optical channel, and the first air blowing system and the second air blowing system blow low-speed gases with different flow rates into the optical channel. An air extraction system is arranged between the first air blowing system and the second air blowing system, and the air extraction system is used to extract part of the low-speed gas in the optical channel. The present invention uses three air paths with different flow rates to protect the optical channel, preventing pulverized coal particles from adhering to the optical elements, and at the same time avoiding the situation that the air path blows directly on the optical window. The extrapolation flow generated by the superposition of the three air paths greatly reduces the pulverized coal particles diffused into the optical channel, improving the stability of the measurement.

Description

Technical Field

[0001] The present invention relates to the field of detecting the fineness of pulverized coal in power plants, and particularly relates to an optical element protection device and method for on-line measurement of the fineness of pulverized coal in power plants. Background Art

[0002] During the operation of coal-fired power plants, the fineness of pulverized coal, as an important parameter for coal combustion in coal-fired power plants, has a great influence on combustion efficiency, carbon content in fly ash, pollutant emissions, etc. Research shows that optimizing after on-line measurement of the fineness of pulverized coal can limit emissions while reducing the carbon content in fly ash.

[0003] Using computer software for image analysis is one of the means for on-line measurement of pulverized coal particles. It directly conducts intuitive detection on the size and shape information of the pulverized coal particles themselves. This measurement method measures the information of the particles themselves without the need to be converted into other related quantities, eliminating possible errors in the conversion process and enabling the measurement results to accurately reflect the particle information. In the process of particle measurement, the light scattering method is commonly used. This method uses a light source to directly irradiate the flow field, and at the same time uses a lens facing the light source to collect particle information. To avoid interference, optical windows are usually installed between the flow field and the light source and the lens. Visualization of the measurement can be achieved through image recognition, and the collected images can be intercepted at any time to extract the characteristics of the particles therein. Although the operation process is intuitive and convenient, the main problem is that the spatial distribution of pulverized coal in the gas-solid mixture is uneven, especially for high-concentration pulverized coal, and the distribution has a certain randomness. At the same time, after the detection system operates in the gas-solid two-phase flow space for a long time, the optical window is easily contaminated. The contaminated window will block part of the light source, reducing the light source quality. At the same time, the imaging shows a certain gray level, bringing trouble to the subsequent image processing and causing great difficulties to the measurement. Summary of the Invention

[0004] Based on the above problems, the purpose of the present invention is to provide an optical element protection device for on-line measurement of the fineness of pulverized coal in power plants. The present invention adopts the following technical solutions:

[0005] The present invention provides an optical element protection device for on-line measurement of the fineness of pulverized coal in power plants, including a measurement channel. Two coaxial and symmetric optical channels are opened at the waist of the measurement channel. A light source is arranged in one of the optical channels, and a signal receiving lens is arranged in the other optical channel. Optical windows are installed at the front parts of the light source and the signal receiving lens. A first air blowing system and a second air blowing system are arranged outside the optical channels. The second air blowing system is close to the measurement channel. The first air blowing system and the second air blowing system blow low-speed gases with different flow rates into the optical channels;

[0006] An air extraction system is arranged between the first air blowing system and the second air blowing system. The air extraction system is used to extract part of the low-speed gas in the optical channels;

[0007] The air curtains formed by the airflows generated by the first air blowing system, the second air blowing system, and the air extraction system inside the optical channel prevent pulverized coal particles from entering the optical channel.

[0008] Preferably, the gas flow rate of the gas blown into the optical channel by the first air blowing system is Q 1 ; the gas flow rate of the gas blown into the optical channel by the second air blowing system is Q 2 ; the gas flow rate of the gas extracted from the optical channel by the air extraction system is Q 3 ;

[0009] The gas flow rates generated by the first air blowing system, the second air blowing system, and the air extraction system satisfy the following relationships:

[0010] Q 1 = 1.2 - 1.5Q 2 ;

[0011] Q 3 > Q 2 ;

[0012] Q 3 < Q 1 + Q 2 .

[0013] Preferably, the first air blowing system includes first air blowing nozzles arranged in a ring on the optical channel, each of the first air blowing nozzles is communicated with a first annular air blowing chamber sleeved outside the optical channel, the first annular air blowing chamber is communicated with a first air inlet pipe, and a first gas flowmeter is arranged on the first air inlet pipe.

[0014] Preferably, the second air blowing system includes second air blowing nozzles arranged in a ring on the optical channel, each of the second air blowing nozzles is communicated with a second annular air blowing chamber sleeved outside the optical channel, the second annular air blowing chamber is communicated with a second air inlet pipe, and a second gas flowmeter is arranged on the second air inlet pipe.

[0015] Preferably, the air extraction system includes air extraction ports arranged in a ring on the optical channel, each of the air extraction ports is communicated with an annular air extraction chamber sleeved outside the optical channel, the annular air extraction chamber is communicated with an air extraction pipe, and a third gas flowmeter is arranged on the air extraction pipe.

[0016] Preferably, the first air blowing system and the second air blowing system blow dry and clean compressed air into the optical channel.

[0017] The present invention also provides a method for protecting optical elements for on-line measurement of pulverized coal fineness in a power plant. The method includes the following steps: when the pulverized coal particles to be measured enter the measurement channel, dry and clean gas is first introduced into the first intake pipe and the second intake pipe. After the dry and clean gas flows evenly through the first annular blowing chamber and the second annular blowing chamber respectively, it is evenly ejected from the first blowing nozzle and the second blowing nozzle. Then, the extraction pipe extracts part of the gas in the optical channel through the annular extraction chamber and the extraction port; the air curtain formed by the three airflows inside the optical channel prevents the pulverized coal particles from entering the optical channel.

[0018] The gas flow rate Q in the first intake pipe is monitored by the first gas flow meter 1 ; the gas flow rate Q in the second intake pipe is monitored by the second gas flow meter 2 ; the gas flow rate Q in the extraction pipe is monitored by the third gas flow meter 3 ;

[0019] By Q 1 and Q 2 The gas flow rate in the first intake pipe is changed through their flow rate relationship, and then through their flow rate relationship with Q3, the gas flow rate in the extraction pipe is changed;

[0020] The gas flow rate Q 1 、Q 2 and Q3 satisfy the following relationship:

[0021] Q 1 = 1.2 - 1.5Q 2 ;

[0022] Q 3 > Q 2 ;

[0023] Q 3 < Q 1 + Q 2 .

[0024] Compared with the prior art, the beneficial technical effects of the present invention:

[0025] The present invention uses three air paths with different flow rates to protect the optical channel, preventing pulverized coal particles from adhering to the optical elements, and at the same time avoiding the situation of direct blowing of the air path to the optical window. The extrapolation flow generated by the superposition of the three air paths greatly reduces the pulverized coal particles diffused into the optical channel, improving the stability of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the drawings.

[0027] Figure 1 It is a schematic structural diagram of the device for protecting optical elements for on-line measurement of pulverized coal fineness in a power plant according to the present invention.

[0028] Description of the reference numerals in the drawings: 1. Measuring channel; 2. Optical channel; 3. Light source; 4. Signal receiving lens; 5. Optical window; 6. First air blowing system; 601. First air blowing nozzle; 602. First annular air blowing chamber; 603. First air inlet pipe; 604. First gas flowmeter; 7. Air extraction system; 701. Air extraction port; 702. Annular air extraction chamber; 703. Air extraction pipe; 704. Third gas flowmeter; 8. Second air blowing system; 801. Second air blowing nozzle; 802. Second annular air blowing chamber; 803. Second air inlet pipe; 804. Second gas flowmeter. Detailed implementation manners

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention 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 invention and are not used to limit the present invention.

[0030] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. The meaning of "several" is one or more unless otherwise specifically defined.

[0031] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0032] Such as Figure 1As shown in the figure, in this embodiment, an optical element protection device for on-line measurement of pulverized coal fineness in a power plant is disclosed, which includes a measurement channel 1. Two coaxial and symmetric optical channels 2 are opened at the waist of the measurement channel 1. A light source 3 is arranged in one of the optical channels 2, and a signal receiving lens 4 is arranged in the other optical channel 2. Optical windows 5 are installed at the front parts of both the light source 3 and the signal receiving lens 4. It is characterized in that: a first air blowing system 6 and a second air blowing system 8 are arranged outside the optical channel 2. The second air blowing system 8 is close to the measurement channel 1. The first air blowing system 6 and the second air blowing system 8 blow low-speed gases with different flow rates into the optical channel 2; an air extraction system 7 is arranged between the first air blowing system 6 and the second air blowing system 8. The air extraction system 7 is used to extract some low-speed gases inside the optical channel 2; the air curtains formed by the airflows generated by the first air blowing system 6, the second air blowing system 8 and the air extraction system 7 inside the optical channel 2 prevent pulverized coal particles from entering the optical channel 2.

[0033] The first air blowing system 6 and the second air blowing system 8 blow dry and clean compressed air into the optical channel 2, and use the dry and clean compressed air as the protective gas. The gas flow rate blown into the optical channel 2 by the first air blowing system 6 is Q 1 ; the gas flow rate blown into the optical channel 2 by the second air blowing system 8 is Q 2 ; the gas flow rate extracted from the optical channel 2 by the air extraction system 7 is Q 3 ; the gas flow rates generated by the first air blowing system 6, the second air blowing system 8 and the air extraction system 7 satisfy the following relationship:

[0034] Q 1 = 1.2 - 1.5Q 2 ;

[0035] Q 3 > Q 2 ;

[0036] Q 3 < Q 1 + Q 2 .

[0037] In this embodiment, the first air blowing system 6 includes first air blowing nozzles 601 arranged in a ring on the optical channel 2. Each first air blowing nozzle 601 is communicated with a first annular air blowing chamber 602 sleeved outside the optical channel 2. The first annular air blowing chamber 602 is communicated with a first air inlet pipe 603, and a first gas flowmeter 604 is arranged on the first air inlet pipe 603.

[0038] In this embodiment, the second air blowing system 8 includes second air blowing nozzles 801 arranged in a ring shape on the optical channel 2. Each second air blowing nozzle 801 communicates with a second annular air blowing chamber 802 sleeved outside the optical channel 2. The second annular air blowing chamber 802 communicates with a second air inlet pipe 803, and a second gas flowmeter 804 is arranged on the second air inlet pipe 803.

[0039] In this embodiment, the air extraction system 7 includes air extraction ports 701 arranged in a ring shape on the optical channel 2. Each air extraction port 701 communicates with an annular air extraction chamber 702 sleeved outside the optical channel 2. The annular air extraction chamber 702 communicates with an air extraction pipe 703, and a third gas flowmeter 704 is arranged on the air extraction pipe 703.

[0040] Based on the specific structure of the above protection device, this embodiment also discloses an on-line measurement optical element protection method for pulverized coal fineness in a power plant. Specifically, when the pulverized coal particles to be measured enter the measurement channel 1, dry and clean gas is first introduced into the first air inlet pipe 603 and the second air inlet pipe 803. After the dry and clean gas uniformly flows through the first annular air blowing chamber 602 and the second annular air blowing chamber 802 respectively, it is evenly ejected from the first air blowing nozzle 601 and the second air blowing nozzle 801. Then, the air extraction pipe 703 extracts part of the gas in the optical channel 2 through the annular air extraction chamber 702 and the air extraction ports 701; the air curtain formed by the three airflows inside the optical channel 2 prevents the pulverized coal particles from entering the optical channel 2.

[0041] Monitor the gas flow rate Q in the first air inlet pipe 603 through the first gas flowmeter 604 1 ; monitor the gas flow rate Q in the second air inlet pipe 803 through the second gas flowmeter 804 2 ; monitor the gas flow rate Q in the air extraction pipe 703 through the third gas flowmeter 704 3 ;

[0042] Through Q 1 and Q 2 Change the gas flow rate in the first air inlet pipe 603 through the flow rate relationship, and then change the gas flow rate in the air extraction pipe 703 through the flow rate relationship between the two and Q3; the gas flow rates Q 1 , Q 2 and Q3 satisfy the following relationships:

[0043] Q 1 = 1.2 - 1.5Q 2 ;

[0044] Q 3 > Q 2 ;

[0045] Q 3 < Q 1 + Q 2。

[0046] Under the combined action of the three airflows, an air flow for the lens will be formed near the optical window 5. The air flow for the lens causes a relatively large degree of air disturbance near the optical window, thereby reducing the probability of coal powder particles adhering to the optical window. In addition to the air flow for the lens, the low-speed airflows entering through the first intake pipe 603 and the second intake pipe 803 will form a propulsion flow tending towards the measurement channel due to their different flow rates. Under the action of the propulsion flow, the probability of coal powder particles diffusing from the measurement channel to the optical channel is greatly reduced.

[0047] Secondly, the position of the light source 3 and the signal receiving lens 4 of the measurement system can be adjusted to make the air flow for the lens completely cover the surface of the optical window. Under the action of the protective gas, the measured coal powder particles will not easily enter the optical channel. Once coal powder particles approach the optical window 5, they will also be affected by the nearby air flow for the lens and will not adhere to the surface of the optical window, improving the measurement stability.

[0048] The embodiments described above are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An optical element protection device for on-line measurement of pulverized coal fineness in a power plant, comprising a measurement channel (1). Two coaxial and symmetric optical channels (2) are opened at the waist of the measurement channel (1). A light source (3) is arranged in one of the optical channels (2), and a signal receiving lens (4) is arranged in the other optical channel (2). Optical windows (5) are installed in front of both the light source (3) and the signal receiving lens (4). It is characterized in that: A first air blowing system (6) and a second air blowing system (8) are arranged outside the optical channel (2). The second air blowing system (8) is close to the measurement channel (1). The first air blowing system (6) and the second air blowing system (8) blow low-speed gases with different flow rates into the optical channel (2). An air extraction system (7) is arranged between the first air blowing system (6) and the second air blowing system (8). The air extraction system (7) is used to extract some low-speed gases in the optical channel (2). An air curtain formed by the airflows generated by the first air blowing system (6), the second air blowing system (8) and the air extraction system (7) inside the optical channel (2) prevents pulverized coal particles from entering the optical channel (2). The gas flow rate blown into the interior of the optical channel (2) by the first gas blowing system (6) is Q 1 ; the gas flow rate blown into the interior of the optical channel (2) by the second gas blowing system (8) is Q 2 ; the gas flow rate extracted from the interior of the optical channel (2) by the air extraction system (7) is Q 3 ; The gas flow rates generated by the first air blowing system (6), the second air blowing system (8) and the air extraction system (7) satisfy the following relationship: Q 1 = 1.2 to 1.5 Q 2 ; Q 3 > Q 2 ; Q 3 <Q 1 + Q 2 。 2. The optical element protection device for on-line measurement of pulverized coal fineness in a power plant according to claim 1, It is characterized in that: The first air blowing system (6) includes a first air blowing nozzle (601) arranged in a ring on the optical channel (2). Each first air blowing nozzle (601) is communicated with a first annular air blowing chamber (602) sleeved outside the optical channel (2). The first annular air blowing chamber (602) is communicated with a first air inlet pipe (603). A first gas flowmeter (604) is arranged on the first air inlet pipe (603).

3. The optical element protection device for on-line measurement of pulverized coal fineness in a power plant according to claim 2, It is characterized in that: The second air blowing system (8) includes a second air blowing nozzle (801) arranged in a ring on the optical channel (2). Each second air blowing nozzle (801) is communicated with a second annular air blowing chamber (802) sleeved outside the optical channel (2). The second annular air blowing chamber (802) is communicated with a second air inlet pipe (803). A second gas flowmeter (804) is arranged on the second air inlet pipe (803).

4. The optical element protection device for on-line measurement of pulverized coal fineness in a power plant according to claim 3, It is characterized in that: The air extraction system (7) includes an air extraction port (701) arranged in a ring on the optical channel (2). Each air extraction port (701) is communicated with an annular air extraction chamber (702) sleeved outside the optical channel (2). The annular air extraction chamber (702) is communicated with an air extraction pipe (703). A third gas flowmeter (704) is arranged on the air extraction pipe (703).

5. The optical element protection device for on-line measurement of pulverized coal fineness in a power plant according to claim 4, It is characterized in that: The first air blowing system (6) and the second air blowing system (8) blow dry and clean compressed air into the interior of the optical channel (2).

6. A method for protecting optical elements in on-line measurement of pulverized coal fineness in a power plant, which is applied to the device for protecting optical elements in on-line measurement of pulverized coal fineness in a power plant according to claim 5, characterized in that: it includes the following steps. After the pulverized coal particles to be measured enter the measurement channel (1), dry and clean gas is first introduced into the first air inlet pipe (603) and the second air inlet pipe (803). After the dry and clean gas is evenly distributed through the first annular air blowing chamber (602) and the second annular air blowing chamber (802), it is evenly ejected from the first air blowing nozzle (601) and the second air blowing nozzle (801). Then, the extraction pipe (703) extracts part of the gas in the optical channel (2) through the annular extraction chamber (702) and the extraction port (701); the air curtain formed by the three airflows inside the optical channel (2) prevents the pulverized coal particles from entering the optical channel (2); Monitor the gas flow rate Q in the first intake pipe (603) through the first gas flowmeter (604). 1 Monitor the gas flow rate Q in the second intake pipe (803) through the second gas flowmeter (804). 2 Monitor the gas flow rate Q in the extraction pipe (703) through the third gas flowmeter (704). 3 ; Through Q 1 and Q 2 The flow rate relationship of and changes the gas flow rate in the first intake pipe (603), and then through the flow rate relationship between the two and Q3, changes the gas flow rate in the extraction pipe (703); Gas flow rate Q 1 , Q 2 and Q3 satisfy the following relationship: Q 1 = 1.2 to 1.5 Q 2 ; Q 3 > Q 2 ; Q 3 <Q 1 + Q 2 。

Images