CN114459829B - Online sampling device and method for air-powder pipe suitable for optical detection technology - Google Patents

Abstract

The invention provides an online sampling device of a wind powder pipe, which is applicable to an optical detection technology, and comprises: the connecting pipe is arranged below the air-powder pipe; an air sealing unit; the packing tube is arranged below the air sealing unit and communicated with the connecting tube, and is used for accommodating falling powder when the air sealing unit stops air guide; the optical detection window is arranged below the sample loading tube and allows light beams of external optical detection equipment to penetrate so as to detect powder positioned on the optical detection window; the back blowing unit is arranged between the sample loading pipe and the optical detection window, and is used for removing powder on the optical detection window through back blowing and comprises a back blowing cavity and a plurality of back blowing air inlets; the back-blowing cavity is of a multi-petal semi-ellipsoidal structure, first focuses of all the semi-ellipsoidal structures are circumferentially and uniformly distributed on a peripheral installation area of the optical detection window, and second focuses of all the semi-ellipsoidal structures are circumferentially and uniformly distributed in the range of the optical detection window; the back-blowing air inlets are arranged on the peripheral installation area, and each back-blowing air inlet is positioned at a first focus of the one-petal semi-ellipsoidal structure.

Description

Online sampling device and method for air-powder pipe suitable for optical detection technology

Technical field

The invention belongs to the technical field of automated detection equipment for coal-fired power stations, and specifically relates to an online sampling device and method for air powder pipes suitable for optical detection technology.

Background technique

The quality of coal fed into the furnace is particularly important for the safety, economy and environmental protection of power plant operations, and determines to a certain extent the operating characteristics of coal-fired boilers and even coal-fired power plants as a whole. With the steady advancement of my country's "building a new power system with new energy as the main body", coal-fired power stations have gradually transformed from the main power supply to a regulated power supply. In order to adapt to the new energy grid's rapid load changes and large peak load demand, Operation mode, rapid combustion adjustment and refined control of boilers have become necessary means, and real-time monitoring of coal quality information entering the furnace has become a new urgent need.

Optical detection technology is very suitable for fast and efficient online detection due to its extremely high precision, extremely fast detection rate, small sample requirements, and non-destructive characteristics. Currently, optical detection technology is used for online detection of coal quality. Methods are also developing rapidly with the increasing demand for flexible and precise combustion control in the context of deep peak shaving. However, optical detection puts forward higher requirements for sampling devices: on the one hand, optical detection requires a window with good cleanliness, so as to maintain good laser transmittance and ensure detection accuracy; on the other hand, optical detection requires The sample amount is small and is easily affected by residual samples, thus affecting the accuracy of the test results.

Contents of the invention

The present invention is carried out to solve the above problems, and the purpose is to provide an online sampling device and method for air pulverized pipes suitable for optical detection technology, which can achieve efficient, fast and accurate sampling of pulverized coal from air pulverized pipes while ensuring maximum protection. Window cleanliness and effective removal of residual sample.

In order to achieve the above object, the present invention adopts the following solutions:

<device>

The present invention provides an air-powder pipe online sampling device suitable for optical detection technology, which is characterized in that it includes: a connecting pipe, connected to the air-powder pipe that transports powder (such as coal powder), and installed below the air-powder pipe; In the air sealing unit, the air outlet is arranged around the inner wall of the connecting pipe, and external air flow is introduced through the air outlet to form a positive pressure in the connecting pipe to prevent the powder from falling; the sample loading pipe is arranged below the air sealing unit and is connected to the connecting pipe. The sealing unit accommodates the falling powder when the air conduction stops; the optical detection window is installed below the sample loading tube to allow the beam of the external optical detection equipment to pass through to detect the powder located on the optical detection window; and backflush The unit is installed between the sample loading tube and the optical detection window. It uses backflush to remove the powder on the optical detection window. It includes a backflush cavity and multiple backflush air inlets; the backflush cavity is set around the bottom of the sample loading tube, forming a The multi-lobed semi-ellipsoid structure forms a backflush space with a hollow interior connected to the sample loading tube and an outward expansion toward the installation area of the optical detection window. The first focal points of all semi-ellipsoid structures are evenly distributed circumferentially in the peripheral installation area of the optical detection window. On the top, the second focus is uniformly distributed circumferentially within the scope of the optical detection window, and the second focus of the semi-ellipsoid structure is located on the other side of the center point of the window relative to the first focus; the backflush air inlet is set in the peripheral installation area, each Each backflush air inlet is located at the first focus of a semi-elliptical structure.

The beneficial effects of the above scheme are:

Due to the above structure, when sampling and testing are required, the backflush air inlet is first used to introduce the backflush air flow multiple times to clean the backflush cavity and optical detection window, and then the air sealing unit stops air intake, and the powder can be It quickly falls and deposits on the optical detection window. Use optical detection technology to detect the powder through the optical detection window to obtain detection data and complete the detection; then, open the backflush air inlet to send in the backflush airflow, and the backflush airflow It is ejected from the first focal point of the ellipsoidal chamber (ellipsoidal structure), and then converges to the second focal point located on the viewing window (optical detection window) through reflection from the cavity wall, and the position and surrounding positions are purged. The backflush airflow ejected from each backflush air inlet is emitted from each ellipsoidal chamber. The backflush air formed overlaps in the main area of the window and the backflush air covers the entire window range, allowing the airflow to blow from different circumferential directions. To the view window, all areas of the entire view window, especially the main area, can be effectively purged, so that all powder remaining on the view window is lifted up and sucked back into the air powder pipe by the air seal unit, realizing the detection of powder. The return of the powder and the blowing of the powder on the window can maximize the guarantee that there is no powder residue in the window detection area, ensuring the cleanliness of the window and the accuracy of the optical detection results; further, the second focus of the ellipsoidal chamber is located at the center point of the window On the other side, the blown airflow can be maintained at a larger inclination angle (non-vertical) to prevent residual powder from sticking to the window due to backflush.

In addition, the entire sampling device uses the positive pressure of the air-powder pipe and the gravity of the powder to conduct direct sampling of the air-powder pipe, which is simple and reliable. When sampling is not performed, due to the existence of the air seal unit, no parts are directly blown by the air powder, thus The service life of the sampling device is guaranteed.

In summary, the online sampling device for air-powder pipes suitable for optical detection technology proposed by the present invention can achieve efficient, fast, and accurate air-powder pipe powder sampling and optical detection while ensuring the cleanliness of the window and the residual sample to the greatest extent. Effective removal, simple structure, long service life, especially when using this device for sampling and testing, no powder is consumed, and there is no need to take the powder out for testing, which not only avoids material loss but also greatly improves the sampling and testing efficiency.

Preferably, the air powder pipe online sampling device suitable for optical detection technology involved in the present invention can also have the following features: an installation cover is provided at the bottom of the backflush unit for sealing the installation of the optical detection window, including: The upper cover ring and lower cover ring of the optical detection window are sealed and clamped from the upper and lower sides, and the fixing member is removable to fasten the upper cover ring and the lower cover ring; among them, the bottom of the backflush air inlet passes through the installation cover. Through this structural design, the optical detection window can be detachably installed, which facilitates maintenance and replacement after long-term use.

Preferably, the air-powder tube online sampling device suitable for optical detection technology involved in the present invention may also include: the backflush cavity includes at least four semi-ellipsoidal structures, and the more the lobes, the more overlapping areas; the backflush cavity has The minimum inner diameter is equal to the inner diameter of the sample loading tube and the inner diameter of the connecting tube.

Preferably, the online powder pipe sampling device suitable for optical detection technology involved in the present invention can also have the following features: the backflush cavity includes a six-lobed semi-ellipsoid structure, which has a moderate number of lobes and is easy to manufacture. And the backflush effect is very good.

Preferably, the air powder tube online sampling device suitable for optical detection technology involved in the present invention can also have the following features: the semi-elliptical structure is not an elliptical shape with a cross section of half, but a semi-elliptical structure that intersects with the sample loading tube. The part of the semi-ellipsoid structure that remains after both the intersection point and the intersection of adjacent semi-ellipsoids are truncated.

Preferably, the air powder tube online sampling device suitable for optical detection technology involved in the present invention can also have the following features: the bottom end of the connecting tube and the upper end of the sampling tube are arranged at a certain distance, and the bottom end of the connecting tube is The upper end of the sample loading tube extends downward and tilts outward, and the upper end of the sample loading tube also extends downward and tilts outward, forming a cone-shaped annular air seal air outlet. A circle of air seals is also formed below the upper end of the sample loading tube. The outer wall of the air-sealed air guide cavity is evenly provided with at least two air-sealed air inlets; the connecting pipe and the sample loading pipe are adjustable and connected through adjusting bolts evenly arranged around them, and the adjusting bolts are along the connecting pipe and the sample loading pipe. Axial extension; the middle part of the adjusting bolt is polygonal, and both the upper and lower parts have threads. By rotating the middle part, the upper and lower screws are rotated to adjust the relative position of the connecting tube and the sample loading tube, thereby adjusting the size of the air seal outlet; air seal outlet , air seal air guide cavity, and air seal air inlet hole together form an air seal unit. The adjusting bolts evenly distributed around the circumference can adjust the relative positions of the connecting tube and the sampling tube in multiple directions to ensure the horizontal and vertical relationship of the assembly. On the other hand, they can also enhance the reliability of the connection and ensure a stable connection of the sampling device. , and also minimizes space occupation, ensuring that the structure of the sampling device is relatively small, thereby reducing the impact on the temperature of the air powder pipe, etc.; by adjusting the rotation of the bolt, the interval between the two components can be changed to match the air seal air intake The air inlet and the air inlet flow form an oblique upward air flow, so that when a suitable air flow is introduced into the air seal inlet, the air powder in the air powder tube is sealed in the tube through the air flow without entering the bottom of the sampling device.

<Method>

Furthermore, the present invention also provides an online sampling method for air-to-powder pipes suitable for optical detection technology. The air-to-powder pipe online sampling device described in any one of the above <device> is used for sampling, and is characterized in that: without sampling When sampling, the air sealing unit is used to continuously introduce air flow to form an air seal to prevent the powder in the air-powder tube from falling into the sampling tube; when sampling, the air sealing unit stops air intake and keeps the backflush air inlet closed, so that the powder falls rapidly , deposited on the optical detection window, and then use optical detection technology to detect the powder through the optical detection window; after the detection is completed, an air sealing unit is used to introduce airflow to form a negative pressure at the sample loading tube, and the powder in the sample loading tube is Most of the powder is sucked into the return air powder pipe. Open the backflush air inlet to introduce a low-pressure backflush airflow, blowing up the powder remaining on the optical detection window so that it is also sucked back into the air powder tube. Tube. This method also has the corresponding beneficial effects described in the above <Device> section.

Preferably, the online powder tube sampling device suitable for optical detection technology involved in the present invention can also have the following feature: before sampling, the backflush air flow is introduced multiple times through the backflush air inlet, and the backflush is Cleaning the cavity and optical detection window before sampling can further ensure the cleanliness of the window, thereby further improving the accuracy of the detection results; after the detection is completed, the backflush air inlet is opened and the backflush is continued for a period of time, and then backflush is introduced intermittently The air flow is back-flushed. By intermittently introducing the back-flushing air flow, the pressure and flow velocity distribution in the back-flushing chamber can be disturbed, thereby cleaning up the remaining pulverized coal more effectively.

Preferably, in the air-to-powder tube online sampling device suitable for optical detection technology involved in the present invention, the specific operation method of intermittently introducing backflush airflow for backflush is: set the backflush airflow pressure to P1, turn on backflush After a certain time t1, close for a few seconds and repeat several times; then adjust the pressure regulating valve to P2 and open the backflush for a certain time t2, then close for a few seconds and repeat several times; then adjust the pressure regulating valve to P3 and open the backflush valve for a certain time t3 Then, turn off for several seconds and repeat several times; P1＜P2＜P3, t1＞(t2+3s)＞(t3+3s). During intermittent backflush, the backflush air pressure increases from small to large. When there is a large amount of residual powder (compared to subsequent backflush conditions), a small pressure airflow can be used to backflush for a relatively long time, which can better remove the residual coal powder. At the same time, it can effectively avoid the pressure sticking of pulverized coal close to the window. When the residual powder is small, short-term backflush with atmospheric pressure can quickly disrupt the chamber pressure, prompting the pulverized coal to leave the window and chamber, and cooperate with the negative pressure suction of the air seal. , and the larger air pressure can also effectively remove the residual coal powder stuck to the window, and the shorter backflush time under the larger air pressure can also prevent the coal powder from being tightly pressed and stuck to the window. In addition, for the closing time (interval time), the low-pressure purge time is long and the interval is short, and the atmospheric pressure purge time is short and the interval is long, which is more conducive to window cleaning.

Preferably, the air-to-powder pipe online sampling device suitable for optical detection technology involved in the present invention can also have the following characteristics: the continuous purging time is 30-60s, P1 is less than 0.5MPa, P3 is less than 1MPa, t1&lt; 30s, 3s＜t3＜8s.

Preferably, the air powder pipe online sampling device suitable for optical detection technology according to the present invention can also have the following feature: the control part is used to control the opening of the air inlet valve of the air seal unit to continuously introduce air flow when no sampling is taken, Form an air seal; use the control unit to control the air inlet valve of the backflush air inlet to open multiple times before sampling to introduce backflush airflow to clean the backflush chamber and optical detection window; use the control unit to control the air seal unit during sampling The air inlet valve is closed and the air inlet valve of the backflush air inlet is closed, causing the powder to fall quickly and deposit on the optical detection window, and then the optical detector is controlled to detect the powder through the optical detection window; the control part is used to detect After completion, control the air inlet valve of the air seal unit to open, form a negative pressure at the sample loading tube, suck most of the powder in the sample loading tube back to the air powder tube, and then control the air inlet from the backflush air inlet. The valve is opened to introduce a low-pressure backflush airflow to remove the powder remaining on the optical detection window. Moreover, specific air pressure regulation is also automatically realized by controlling the corresponding intake valve through the control unit. Through this, fully automated operation and precise control of the processes of pre-sampling cleaning, sampling, detection, and post-detection cleaning are realized, which greatly improves detection efficiency and enables powder detection to be carried out in a timely, accurate and reliable manner.

Description of drawings

Figure 1 is a schematic structural diagram of an online powder pipe sampling device suitable for optical detection technology according to an embodiment of the present invention;

Figure 2 is a schematic diagram of the installation position of the online powder pipe sampling device suitable for optical detection technology according to the embodiment of the present invention;

Figure 3 is a perspective view of an online powder pipe sampling device suitable for optical detection technology according to an embodiment of the present invention;

Figure 4 is a cross-sectional view of an online powder pipe sampling device suitable for optical detection technology according to an embodiment of the present invention;

Figure 5 is a cross-sectional view of the sample loading tube and the backflush unit formed at the bottom of the sample loading according to the embodiment of the present invention;

Figure 6 is a perspective view of the sample loading tube and backflush unit involved in the embodiment of the present invention;

Figure 7 is a bottom view of the structure of Figure 5;

Figure 8 is a schematic diagram of the working principle of the backflush unit involved in the embodiment of the present invention;

Figure 9 is a schematic diagram of the coverage of the optical detection window by the backflush gas according to the embodiment of the present invention.

Detailed ways

The online sampling device and method for air-to-powder pipes suitable for optical detection technology involved in the present invention will be described in detail below with reference to the accompanying drawings.

<Example>

As shown in Figures 1 to 4, the air-to-powder pipe online sampling device 10 suitable for optical detection technology is installed below the air-to-powder pipe F for transporting pulverized coal in a coal-fired power station. It includes a connecting pipe 11, a gas seal unit 12, and a sampling pipe. 13. Optical detection window 14, backflush unit 15 and installation cover 16.

The connecting pipe 11 is connected with the transverse section of the air powder pipe F, and is sealed and installed at the opening of the lower side wall of the air powder pipe F.

The air outlet 12a of the air sealing unit 12 is arranged around the inner wall of the connecting pipe 11, and external air flow is introduced through the air outlet 12a to form a positive pressure in the connecting pipe 11 to prevent the pulverized coal from falling.

The sample loading pipe 13 is arranged below the gas sealing unit 12 and is connected with the connecting pipe 11 to accommodate the fallen coal powder as the sample to be measured when the gas sealing unit 12 stops introducing air flow. The sample loading tube 13 has a sandwich structure, with a base 13a on the periphery. The upper part of the base 13a is arranged around the lower outer wall of the connecting tube 11, and is connected to the upper convex part of the connecting tube 11 through the adjusting bolt 12d, and is sealed by an air sealing ring 12e. For sealing, the lower part of the base 13a is evenly provided with four air-sealing air inlet holes 12b in the circumferential direction; the interlayer is hollow to form a ring-shaped annular air-sealing air guide cavity 12c; the inner periphery corresponds to the inner wall of the connecting tube 11 to form a sample loading tube 13, and the inner wall 13b has the same diameter as the inner wall of the connecting pipe 11.

As shown in Figures 2 and 3, the bottom end of the connecting tube 11 is spaced a certain distance from the upper end of the sample loading tube 13. The bottom end of the connecting tube 11 extends downward and obliquely outward, and the upper end of the sample loading tube 13 also extends downward and outward. They extend outward obliquely and together form a cone-shaped annular air seal air outlet 12a. The outside of the air seal air outlet 12a is an air seal air guide cavity 12c. The outer wall of the air seal air guide cavity 12c is provided with an air seal air inlet hole 12b. The air seal air inlet 12b is connected to the external air inlet pipe. The air flow enters the air seal air guide cavity 12c through the air seal air inlet hole 12b, and then flows out from the air seal air outlet 12a, thereby forming a positive pressure above the air seal air outlet 12a to prevent the coal powder from falling into the sampling tube 13. A negative pressure is formed below the air outlet 12a. The air seal air outlet 12a, the air seal air guide cavity 12c, the air seal air inlet 12b, the adjusting bolt 12d, and the air seal sealing ring 12e together form the air seal unit 12.

The connecting pipe 11 and the sample loading pipe 13 are adjustable and connected through adjusting bolts 12d evenly arranged around them. The adjusting bolts 12d extend along the axial direction of the connecting pipe 11 and the sample loading pipe 13; the middle part of the adjusting bolt 12d is polygonal, with upper and lower parts. Thread, by rotating the middle part to drive the upper and lower screws to rotate and adjust the relative positions of the connecting tube 11 and the sample loading tube 13, thereby adjusting the size of the air seal outlet 12a. In this embodiment, four adjusting bolts 12d are evenly distributed in the circumferential direction, and each adjusting bolt 12d is correspondingly arranged above an air seal air inlet 12b. The air seal can be adjusted according to the position of the adjusting bolt 12d to form a required air seal.

The optical detection window 14 is installed below the sample loading tube 13 to allow the light beam of the external optical detection equipment to pass through to detect the coal powder located on the optical detection window 14. In this embodiment, the optical detection window 14 is made of sapphire and has relatively high performance. It has good mechanical strength, strong wear resistance and a single structure. It is suitable for a variety of coal quality detection methods. In addition, the thickness of sapphire is 3~5mm. Specifically, in this embodiment, a laser detection device is used to emit laser light to detect the coal quality of the pulverized coal located on the optical detection window 14 .

The backflush unit 15 is arranged between the sample tube 13 and the optical detection window 14, and the coal powder on the optical detection window 14 is removed through backflush. The backflush unit 15 includes a backflush chamber 151 and a plurality of backflush air inlets 152 .

As shown in Figures 2 to 7, the backflush chamber 151 is arranged around the bottom of the sample loading tube 13, and is integrally formed with the sample loading tube 13. It has a multi-lobed semi-ellipsoid structure, forming an internal hollow that communicates with the sample loading tube 13, and the periphery faces the optical detection. The installation area of the window 14 is an expanded backflush space (that is, a multi-lobed semi-elliptical structure dug out from the inner wall of the bottom of the sample tube 13 along the radial direction). The semi-ellipsoid structure 151a is not an ellipse with half the cross-section, but the remaining part of the semi-ellipsoid structure 151a (about a quarter) that is cut off at the intersection with the sample tube 13 and at the intersection of adjacent semi-ellipsoids. Ellipsoid chamber of ellipsoid). In this embodiment, the backflush chamber 151 includes a total of six semi-elliptical structures 151a. The minimum inner diameter of the backflush chamber 151 is equal to the inner diameter of the sample loading tube 13 and the inner diameter of the connecting tube 11.

As shown in Figures 4 and 8, the first focal points of all semi-ellipsoidal structures 151a are evenly distributed circumferentially on the peripheral installation area of the optical detection window 14. In this embodiment, there are a total of six backflush air inlets 152, each of which is The air inlets 152 are located at the first focus of a semi-elliptical structure 151a. As shown in FIGS. 8 and 9 , the second focus is uniformly distributed circumferentially within the detection area in the middle of the optical detection window 14 , and the second focus of the semi-ellipsoid structure 151 a is located on the other side of the center point of the optical detection window relative to the first focus. Due to such a structure, after the backflush airflow introduced by the backflush air inlet 152 at the first focus enters the semi-ellipsoid structure 151a, the airflow in all directions will converge to the second focus, thereby maximizing the optical impact. The detection window 14 is effectively purged to remove the coal powder on the optical detection window 14 after sampling and detection. Since the window is the coal quality detection area, the cleaning of the window is particularly critical. The focusing purge method of the ellipsoid chamber can effectively clean the window and ensure detection accuracy.

As shown in FIG. 4 , the installation cover 16 is provided at the bottom of the backflush unit 15 for sealing installation of the optical detection window 14 . It includes an upper cover ring 161 , a lower cover ring 162 and a plurality of fixing members 163 . The upper cover ring 161 and the lower cover ring 162 seal and clamp the optical detection window 14 from the upper and lower sides. The edges of the optical detection window 14 are provided with sealing rings in contact with the upper cover ring 161 and the lower cover ring 162 . One set of fasteners 163 is used to detachably fasten the upper cover ring 161 and the lower cover ring 162, and the other set of fasteners fastens the outer edge of the installation cover 16 to the outer edge of the backflush unit 15; this embodiment , the fixing part 163 is a screw fixing part. The bottom of the backflush air inlet 152 penetrates the installation cover 16 and is connected to the external air inlet pipe.

The above is the specific structure of the air-to-powder pipe online sampling device 10 provided in this embodiment. Furthermore, this embodiment also provides a method for using the air-to-powder pipe online sampling device 10 to perform automated online detection. Specifically, the control unit performs the following operations. :

When not sampling, keep the air seal air inlet valve on the external air inlet pipe connected to the air seal air inlet hole 12b open, continuously introduce air flow with a pressure of 0.3 to 0.7 MPa, and form an upward positive pressure air seal at the connecting pipe 11. Prevent the coal powder in the air powder pipe F from falling into the sample loading pipe 13.

Before sampling, open the backflush air inlet valve on the external air inlet pipe of the backflush air inlet 152 multiple times (3-5 times), and introduce a larger backflush with a pressure of 0.5 to 0.7MPa (0.7MPa is used in this embodiment). The air flow lasts for 2 to 5 seconds each time with an interval of 3 seconds to clean the optical detection window 14 before sampling.

During sampling, the air seal air inlet valve of the air seal unit 12 is closed, so that the backflush air inlet valve on the external air inlet pipe of the backflush air inlet 152 remains closed, and the pulverized coal falls rapidly, deposits on the optical detection window 14 and The rapid accumulation covers the optical detection window 14 (the sample loading tube 13 is also quickly filled with coal powder), and then the laser detection equipment emits a beam through the optical detection window 14 to quickly detect the coal powder to obtain optical detection data.

After the test is completed, open the air seal air inlet valve of the air seal unit 12 to introduce an air flow of 0.5 to 0.7 MPa. An upward positive pressure air seal is formed at the connecting pipe 11 to prevent the pulverized coal from falling from the air powder pipe F. Correspondingly, in the air seal Negative pressure is formed at the sampling tube 13 below, thereby sucking up the coal powder at the sampling tube 13, backflush chamber 151 and optical detection window 14, and then blowing it back to the air powder tube F, thus realizing the previous sampling detection. In the pre-cleaning of the coal powder, most of the coal powder is sent back to the air powder pipe F, but there is still a certain amount of residual coal powder attached to the surface of the optical detection window 14. Then, open the backflush air inlet valve of the backflush air inlet 152 to introduce a backflush airflow with a small pressure of 0.3MPa to continuously purge, blowing up the pulverized coal remaining on the optical detection window 14 so that it is also sucked back into the air. Powder pipe F (the backflush air pressure is relatively small. On the one hand, the backflush is used to effectively blow up the pulverized coal in the backflush cavity 151, thereby speeding up the return of the pulverized coal in the chamber to the air pulverizer pipe F and reducing the amount of pulverized coal in the chamber. Residence time; on the other hand, smaller pressure is also used to prevent excessive air pressure from pressing part of the pulverized coal close to the optical detection window 14 on the window, making subsequent removal more difficult).

After the detection is completed, the backflush air inlet 152 is opened and the backflush air inlet 152 is continuously purged for a period of time (30-60s), and then the backflush air flow is introduced intermittently for backflushing to disrupt the pressure and flow rate distribution in the backflush chamber 151, thereby removing the remaining coal. Clean the powder: Adjust the backflush air pressure to 0.3MPa, open the backflush intake valve and backflush for 15 seconds, then close it for 5s, repeat 3 times; then adjust the pressure regulating valve to 0.5MPa, open the backflush intake valve and backflush for 10s Then, close it for 10 seconds and repeat it three times; then adjust the pressure regulating valve to 0.7MPa, open the backflush intake valve and blow back it for 5 seconds, then close it for 15 seconds and repeat it three times. The principle is that the low-pressure purge time is long and the interval is short, and the atmospheric pressure purge time period is long and the interval is long; the pressure is from small to large. When there is a lot of residual coal powder, the small-pressure air flow and the relatively long time backflush can better remove the residual coal. While removing the pulverized coal, it effectively avoids the pressure sticking of the pulverized coal close to the optical detection window 14. When the remaining pulverized coal is small, short-term backflush with atmospheric pressure can quickly disrupt the chamber pressure and promote the separation of the pulverized coal from the optical detection window 14 and the chamber. , combined with the negative pressure suction of the air seal, the higher air pressure can also effectively remove the residual coal powder stuck to the optical detection window 14. The shorter backflush time under the higher air pressure can also prevent the coal powder from being tightly pressed and stuck to the optical detection window 14. on the optical detection window 14.

In the process of using the control unit to perform the above operations, the sampling frequency can be controlled by regulating the formation of the air seal, and adjusting the backflush can ensure the representativeness of the sampling, avoid the influence of the previously sampled coal powder on the detection, and ensure the accuracy of the detection results.

The above are only examples of the technical solutions of the present invention. The online sampling device and method of air powder pipe F suitable for optical detection technology involved in the present invention are not limited to the structure described above, but are subject to the scope defined by the claims. Any modifications, additions or equivalent substitutions made by those skilled in the art to which the present invention belongs are within the scope of the claims of the present invention.

Claims (10)

1. Wind powder pipe on-line sampling device suitable for optical detection technique, its characterized in that includes:

the connecting pipe is connected with a powder pipe for conveying powder and is arranged below the powder pipe;

the air sealing unit is provided with an air outlet which surrounds the inner wall of the connecting pipe, and external air flow is led in through the air outlet to form positive pressure in the connecting pipe so as to prevent the powder from falling;

the gas seal unit is provided with a connecting pipe, and is used for connecting the powder falling into the gas seal unit;

an optical detection window which is arranged below the sample loading tube and allows light beams of external optical detection equipment to pass through so as to detect the powder positioned on the optical detection window; and

the back blowing unit is arranged between the sample loading pipe and the optical detection window, and is used for removing the powder on the optical detection window through back blowing and comprises a back blowing cavity and a plurality of back blowing air inlets; the back blowing cavity is arranged around the bottom of the sample loading pipe and is of a multi-petal semi-ellipsoidal structure, a back blowing space which is hollow inside, communicated with the sample loading pipe and has the periphery facing the outside of the installation area of the optical detection window is formed, first focuses of all the semi-ellipsoidal structure are circumferentially uniformly distributed on the peripheral installation area of the optical detection window, second focuses of all the semi-ellipsoidal structure are circumferentially uniformly distributed in the range of the optical detection window, and the second focuses of the semi-ellipsoidal structure are positioned on the other side of the center point of the window relative to the first focuses; the back-blowing air inlets are arranged on the peripheral installation area, and each back-blowing air inlet is positioned at the first focus of the half-ellipsoidal structure.

2. The wind-powder tube on-line sampling apparatus for optical detection technology of claim 1, further comprising:

the installation lid sets up blowback unit bottom for sealing installation optical detection window includes: an upper cover ring and a lower cover ring of the optical detection window are clamped and fixed in a sealing manner from the upper side and the lower side, and a fixing piece for fastening and connecting the upper cover ring and the lower cover ring is detachable;

the bottom of the back blowing air inlet penetrates through the mounting cover.

3. The wind-powder tube on-line sampling device suitable for optical detection technology according to claim 1, wherein:

the back-flushing cavity comprises at least four semiellipsoidal structures, and the minimum inner diameter of the back-flushing cavity is equal to the inner diameter of the sample loading tube and the inner diameter of the connecting tube.

4. The wind-powder tube on-line sampling device suitable for optical detection technology according to claim 1, wherein:

wherein, the blowback chamber includes six lamella the semiellipsoidal structure.

5. The wind-powder tube on-line sampling device suitable for optical detection technology according to claim 1, wherein:

the semi-ellipsoidal structure is not an ellipse with a half section, but a part of the semi-ellipsoidal structure which remains after the intersection with the sample loading tube and the intersection of the adjacent semi-ellipsoids are cut off.

6. The wind-powder tube on-line sampling device suitable for optical detection technology according to claim 1, wherein:

the bottom end of the connecting pipe and the upper end of the sample filling pipe are arranged at a certain distance, the bottom end of the connecting pipe extends downwards and outwards in an inclined mode, the upper end of the sample filling pipe also extends downwards and outwards in an inclined mode, a circle of conical annular air seal air outlet is formed by surrounding the connecting pipe together, a circle of air seal air guide cavity is formed in the lower portion of the outer side of the upper end of the sample filling pipe, and at least two air seal air inlet holes are uniformly formed in the outer wall of the air seal air guide cavity;

the connecting pipe is adjustably connected with the sample loading pipe through adjusting bolts which are uniformly arranged on the periphery, and the adjusting bolts extend along the axial directions of the connecting pipe and the sample loading pipe; the middle part of the adjusting bolt is polygonal, the upper part and the lower part of the adjusting bolt are both provided with threads, and the upper screw and the lower screw are driven to rotate by rotating the middle part to adjust the relative position of the adjusting connecting pipe and the sample loading pipe, so that the size of the air seal air outlet is adjusted;

the air seal air outlet, the air seal air guide cavity and the air seal air inlet hole jointly form the air seal unit.

7. An online sampling method for an air-powder tube suitable for an optical detection technology, which adopts the online sampling device for the air-powder tube according to any one of claims 1 to 6 for sampling, and is characterized in that:

when the sampling is not performed, the air seal unit is adopted to continuously guide air flow to form an air seal, so that powder of the air powder pipe is prevented from falling into the sample loading pipe;

when sampling is performed, the air seal unit stops air inlet, a back blowing air inlet is kept closed, powder rapidly falls down and is deposited on an optical detection window, and then the powder is detected by utilizing an optical detection technology through the optical detection window;

after detection is completed, air flow is led in by adopting the air seal unit, negative pressure is formed at the position of the sample loading pipe, most of powder in the sample loading pipe is sucked back to the air powder pipe, the back blowing air inlet is opened to introduce back blowing air flow with small air pressure, and the powder remained on the optical detection window is blown up to be sucked back to the air powder pipe.

8. The on-line sampling method for air-powder tubes suitable for optical detection technology according to claim 7, wherein the method comprises the following steps:

before sampling, introducing back-blowing air flow for a plurality of times through a back-blowing air inlet, and cleaning an optical detection window before sampling;

and after the detection is finished and the back-flushing air inlet is opened for a period of time for continuous purging, intermittently introducing back-flushing air flow to carry out back-flushing.

9. The on-line sampling method for air-powder tubes suitable for optical detection technology according to claim 8, wherein the method comprises the following steps:

the specific operation method for intermittently introducing back-blowing air flow to carry out back blowing comprises the following steps: setting the back-blowing air pressure as P1, opening back-blowing for a certain time t1, closing for a plurality of seconds, and repeating for a plurality of times; then regulating the pressure regulating valve to P2, opening back blowing for a certain time t2, closing for a plurality of seconds, and repeating for a plurality of times; then regulating the pressure regulating valve to P3, opening the back flushing valve for a certain time t3, closing for a plurality of seconds, and repeating for a plurality of times; p1 < P2 < P3, t1 > (t2+3s) > (t3+3s).

10. The on-line sampling method for air-powder tubes suitable for optical detection technology according to claim 7, wherein the method comprises the following steps:

the control part is used for controlling the air inlet valve of the air sealing unit to open when sampling is not performed so as to continuously guide air flow, so that air sealing is formed; the control part is adopted to control the air inlet valve of the back-blowing air inlet to open for a plurality of times before sampling so as to introduce back-blowing air flow, and the back-blowing cavity and the optical detection window are cleaned; the control part is adopted to control the closing of the air inlet valve of the air seal unit and the closing of the air inlet valve of the back blowing air inlet when sampling is carried out, so that powder falls down rapidly, the powder is deposited on the optical detection window, and then the optical detector is controlled to detect the powder through the optical detection window; and after detection, the control part is used for controlling the air inlet valve of the air sealing unit to open, negative pressure is formed at the position of the sample loading pipe, most of powder in the sample loading pipe is sucked back to the air powder pipe, then the air inlet valve of the back blowing air inlet is controlled to open, so that back blowing air flow with small air pressure is introduced, and the powder remained on the optical detection window is removed.