Coal pulverizing system coal mill inlet air volume measuring device

Abstract

The invention belongs to the field of air velocity measurement, and particularly relates to a coal pulverizing system coal mill inlet air volume measuring device which is characterized in that when a first valve is opened and a second valve is closed, a first air duct transmits flow field disordered gas to an air flow equalizer, and the air flow equalizer equalizes the introduced flow field disordered gas; the gas after flow equalization is transmitted to the second air duct, and the gas in the second air duct is transmitted to the connecting pipe through the speed measuring pipe; a static pressure value in the second air duct, a differential pressure value in the speed measuring pipe and a temperature in the second air duct are obtained, the medium flow speed is calculated, whether the speed measuring pipe is blocked or not is judged according to the calculated medium flow speed, if the speed measuring pipe is blocked, the first valve is closed, the second valve is opened, and compressed air enters the speed measuring pipe through the sweeping air pipe to sweep the speed measuring pipe; the problem that in the prior art, air volume measurement of a boiler pulverizing system is inaccurate due to air pipe blockage is solved.

Description

Technical Field

[0001] This application belongs to the field of air velocity measurement, and particularly relates to an air volume measurement device at the inlet of a coal mill in a pulverizing system. Background Art

[0002] China is still in the process of low-carbon energy transformation, and thermal power generation remains an important foundation for maintaining the stable operation of the power system. The pulverizing system is an important auxiliary system in thermal power generation enterprises. Restricted by the initial investment scale of thermal power plants, the designs of boiler flue gas and air systems and pulverizing systems are mostly compactly arranged. This makes the working conditions of the current air volume measurement devices in boiler pulverizing systems unable to reach their proper working conditions, and the air volume measurement devices in the existing technologies have complex structures, resulting in problems such as blockage of connecting pipes, inaccurate air volume measurement during actual operation, and poor stability of measurement data. Summary of the Invention

[0003] To solve the problem of inaccurate air volume measurement in the boiler pulverizing system due to air duct blockage in the existing technology, an air volume measurement device at the inlet of a coal mill in a pulverizing system is proposed;

[0004] An air volume measurement device at the inlet of a coal mill in a pulverizing system includes: a first air duct, an air flow equalizer, a first pressure transmitter, a thermocouple, a second air duct, a pitot tube, a connecting pipe, a first valve, a cleaning air duct, a second valve, a second differential pressure transmitter, a host computer, and a compressed air system;

[0005] The outlet of the first air duct is connected to the inlet of the air flow equalizer, and the outlet of the air flow equalizer is connected to the inlet of the second air duct; the first pressure transmitter and the thermocouple are both fixed inside the second air duct. A first through hole is provided on the side wall of the second air duct. One end of the pitot tube passes through the first through hole and is arranged inside the second air duct, and the other end of the pitot tube is connected to the inlet of the connecting pipe. A first valve and a second differential pressure transmitter are arranged at the outlet of the connecting pipe; a second through hole is provided on the side wall of the pitot tube. The outlet of the cleaning air duct is connected to the pitot tube through the second through hole. A second valve is arranged at the inlet of the cleaning air duct, and the inlet of the cleaning air duct is connected to the outlet of the compressed air system; the connection between the pitot tube and the first through hole is sealed, the connection between the pitot tube and the inlet of the connecting pipe is sealed, and the connection between the pitot tube and the outlet of the cleaning air duct is sealed;

[0006] When the first valve is open and the second valve is closed, the first air duct transmits the gas with a chaotic flow field to the air flow conditioner. The air flow conditioner equalizes the flow of the incoming gas with a chaotic flow field and transmits the equalized gas to the second air duct. The gas in the second air duct is transmitted to the connecting pipe through the velocity measuring tube. The first pressure transmitter is used to obtain the static pressure inside the second air duct, the second differential pressure transmitter is used to obtain the differential pressure inside the velocity measuring tube, and the thermocouple is used to obtain the temperature inside the second air duct. The upper computer is used to obtain the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube, and the temperature inside the second air duct, calculate the medium flow velocity based on the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube, and the temperature inside the second air duct, and determine whether the velocity measuring tube is blocked according to the calculated medium flow velocity. If so, close the first valve and open the second valve to allow compressed air to enter the velocity measuring tube through the cleaning air duct to clean the velocity measuring tube.

[0007] The beneficial effects of this application are as follows: A coal pulverizing system mill inlet air volume measuring device of this application calculates the medium flow velocity based on the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube, and the temperature inside the second air duct, and determines whether the velocity measuring tube is blocked according to the calculated medium flow velocity. If the velocity measuring tube is blocked, the first valve at the connecting pipe is controlled to close and the second valve at the cleaning air duct is opened, and the velocity measuring tube is cleaned with compressed air, which can effectively solve the problem of inaccurate air volume measurement in the boiler coal pulverizing system caused by the blockage of the velocity measuring tube; it can accurately and stably measure the true wind speed in the air duct; at the same time, this system has the advantages of simple structure, low operation and maintenance costs, reliable system operation, and can operate for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic structural diagram of a coal pulverizing system mill inlet air volume measuring device according to a specific embodiment of this application;

[0009] Figure 2 is Figure 1 The sectional structure diagram at A-A in SPECIFIC EMBODIMENTS

[0010] Specific Embodiment 1: The following will combine the attached drawings in the embodiments of the present invention Figure 1 to the attached Figure 2 to describe this embodiment, and clearly and completely describe the technical solutions in the embodiments of the present invention:

[0011] A coal pulverizing system mill inlet air volume measuring device includes: a first air duct 1, an air flow conditioner 2, a first pressure transmitter 3, a thermocouple 4, a second air duct 5, a velocity measuring tube 6, a connecting pipe 8, a first valve 7, a cleaning air duct 9, a second valve 10, a second differential pressure transmitter, an upper computer, and a compressed air system;

[0012] The air outlet of the first air duct 1 is connected to the air inlet of the air flow equalizer 2, and the air outlet of the air flow equalizer 2 is connected to the air inlet of the second air duct 5; the first pressure transmitter 3 and the thermocouple 4 are both fixed inside the second air duct 5, a first through hole is provided on the side wall of the second air duct 5, one end of the pitot tube 6 passes through the first through hole and is arranged inside the second air duct 5, and the other end of the pitot tube 6 is connected to the air inlet of the connecting pipe 8. A first valve 7 and a second differential pressure transmitter are provided at the air outlet of the connecting pipe 8; a second through hole is provided on the side wall of the pitot tube 6, and the air outlet of the cleaning air duct 9 is connected to the pitot tube 6 through the second through hole. A second valve 10 is provided at the air inlet of the cleaning air duct 9, and the air inlet of the cleaning air duct 9 is connected to the air outlet of the compressed air system; the connection between the pitot tube 6 and the first through hole is sealed, the connection between the pitot tube 6 and the air inlet of the connecting pipe 8 is sealed, and the connection between the pitot tube 6 and the air outlet of the cleaning air duct 9 is sealed.

[0013] When the first valve 7 is open and the second valve 10 is closed, the first air duct 1 transports the gas with chaotic flow field to the air flow equalizer 2. The air flow equalizer 2 equalizes the chaotic gas flow field introduced, and transports the equalized gas to the second air duct 5. The gas in the second air duct 5 is transported to the connecting pipe 8 through the pitot tube 6; the first pressure transmitter 3 is used to obtain the static pressure inside the second air duct 5, the second differential pressure transmitter is used to obtain the differential pressure inside the pitot tube 6, and the thermocouple 4 is used to obtain the temperature inside the second air duct 5; the upper computer is used to obtain the static pressure value inside the second air duct 5, the differential pressure value inside the pitot tube 6, and the temperature inside the second air duct 5, calculate the medium flow velocity according to the static pressure value inside the second air duct 5, the differential pressure value inside the pitot tube 6, and the temperature inside the second air duct 5, and judge whether the pitot tube is blocked according to the calculated medium flow velocity. If so, close the first valve 7 and open the second valve 10 to allow compressed air to enter the pitot tube 6 through the cleaning air duct 10 to clean the pitot tube 6.

[0014] Specifically, the upstream air flow with chaotic flow field distribution enters the air flow equalizer 2 through the first air duct 1. Through the flow equalizing and guiding action of the air flow equalizer 2, the air flow becomes uniform and stable in the flow field. When the air flow with this flow stability characteristic flows through the pitot tube 6, stable test conditions can be formed. The pitot tube 6 is hermetically connected to the connecting pipe 8, and the second differential pressure transmitter obtains the differential pressure inside the pitot tube 6; the air flow equalizer 2 is connected to the second air duct 5; during normal operation of the device, the first valve 7 on the connecting pipe 8 is in the open state. When the upper computer determines that the pitot tube 6 is blocked according to the calculated medium flow velocity, the first valve 7 on the connecting pipe 8 should be closed at this time, and the second valve 10 on the cleaning air duct 9 should be opened to use compressed air to purge the blocked pitot tube 6; after the cleaning is completed, the second valve 10 on the cleaning air duct 9 is closed, and the first valve 7 on the connecting pipe 8 is opened, and the measurement system resumes operation.

[0015] Further, the method for calculating the medium flow velocity according to the static pressure value inside the second air duct 5, the differential pressure value inside the pitot tube 6, and the temperature inside the second air duct 5 is as follows: Among them, W is the medium flow velocity, and k d is the calibration coefficient of the velocity measuring tube, and H d is the internal pressure difference of the velocity measuring tube 6, and t a is the internal temperature of the second air duct 5, Pat is the current atmospheric pressure, and ρ a,st is the air density under standard conditions, and Pa is the internal static pressure value of the second air duct 5.

[0016] Furthermore, the method for judging whether the velocity measuring tube is blocked according to the calculated medium flow velocity is: judging whether the calculated medium flow velocity belongs to the set flow velocity range, otherwise the velocity measuring tube is blocked.

[0017] Furthermore, a plurality of flow equalizing grids are fixed inside the air flow equalizer 2 along the length direction of the air flow equalizer 2; the flow equalizing grids are of a mesh structure and are used for equalizing the air transmitted by the first air duct 1 to obtain uniformly flowing equalized air.

[0018] Specifically, the flow equalizing grids inside the air flow equalizer 2 can process the upstream flow field with a complex distribution into a downstream flow field with simple and stable flow, creating a favorable measurement environment for the velocity measuring tube 6 and the connecting pipe 8, and improving the accuracy of the air volume measuring device at the inlet of the coal mill in the coal pulverizing system; in actual operation, the thickness of the flow equalizing grids can be set according to the actual working conditions to improve the flow equalizing effect on the upstream flow field with a complex distribution.

[0019] Furthermore, the flow equalizing grids are made of carbon steel.

[0020] Specifically, carbon steel can withstand high temperatures, which is beneficial to the stable operation of the device of the present application.

[0021] Furthermore, the first air duct 1 is connected to the air flow equalizer 2 by bolts, and the air flow equalizer 2 is connected to the second air duct 5 by bolts. Specifically, the bolt connection method is convenient for later maintenance, has low operation and maintenance costs, and strong practicability.

[0022] The present invention is applicable to the original design and operation transformation process of the air volume measuring device in the boiler flue gas system and the coal pulverizing system, especially for the transformation of power plants where the original flue gas system and coal pulverizing system are compactly arranged and the air volume measuring device does not meet the design and installation conditions. It can improve the comprehensive benefits brought by the control accuracy of the boiler and its coal pulverizing system.

[0023] Although the present invention has been described herein with reference to particular embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Accordingly, it should be understood that numerous modifications may be made to the exemplary embodiments, and other arrangements may be devised, without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein may be combined in ways different from those described in the original claims. It should also be understood that the features described in connection with a separate embodiment may be used in other described embodiments.

Claims

1. A device for measuring the air volume at the inlet of a coal mill in a pulverizing system, characterized in that: include: The first air duct, the air flow equalizer, the first pressure transmitter, the thermocouple, the second air duct, the velocity measuring tube, the connecting tube, the first valve, the cleaning air duct, the second valve, the second differential pressure transmitter, the host computer and the compressed air system; The air outlet of the first air duct is connected to the air inlet of the air equalizer, and the air outlet of the air equalizer is connected to the air inlet of the second air duct; the first pressure transmitter and the thermocouple are both fixed inside the second air duct, and the side wall of the second air duct is provided with a first through hole, one end of the velocity measuring tube passes through the first through hole and is provided inside the second air duct, and the other end of the velocity measuring tube is connected to the air inlet of the connecting pipe, and the air outlet of the connecting pipe is provided with a first valve and a second differential pressure transmitter; a second through hole is provided on the side wall of the velocity measuring tube, and the air outlet of the cleaning air duct is connected to the velocity measuring tube through the second through hole, and a second valve is provided at the air inlet of the cleaning air duct, and the air inlet of the cleaning air duct is connected to the air outlet of the compressed air system; the connection between the velocity measuring tube and the first through hole is sealed, the connection between the velocity measuring tube and the air inlet of the connecting pipe is sealed, and the connection between the velocity measuring tube and the air outlet of the cleaning air duct is sealed; When the first valve is opened and the second valve is closed, the first air duct transmits the chaotic gas in the flow field to the air equalizer, the air equalizer equalizes the chaotic gas in the flow field introduced, and transmits the equalized gas to the second air duct, and the gas in the second air duct is transmitted to the connecting pipe through the velocity measuring tube; the first pressure transmitter is used to obtain the static pressure inside the second air duct, the second differential pressure transmitter is used to obtain the differential pressure inside the velocity measuring tube, and the thermocouple is used to obtain the internal temperature of the second air duct; the host computer is used to obtain the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube and the internal temperature of the second air duct, calculate the medium flow rate according to the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube and the internal temperature of the second air duct, and judge whether the velocity measuring tube is blocked according to the calculated medium flow rate. If the first valve is closed and the second valve is opened, the compressed air enters the velocity measuring tube through the cleaning air duct to clean the velocity measuring tube.

2. The device for measuring air volume at the coal mill inlet of a pulverizing system according to claim 1, characterized in that: The method for calculating the medium flow rate according to the static pressure value inside the second air duct, the differential pressure value inside the velocity measuring tube and the temperature inside the second air duct is: Where W is the medium flow rate, k d is the calibration coefficient of the velocity tube, H d is the pressure difference inside the velocity tube, t a is the internal temperature of the second air duct, Pat is the current atmospheric pressure, ρ a,st is the air density under standard conditions, and Pa is the static pressure value inside the second air duct.

3. The device for measuring air volume at the coal mill inlet of a pulverizing system according to claim 3 is characterized in that: The method for judging whether the velocity measuring tube is blocked according to the calculated medium flow velocity is as follows: judging whether the calculated medium flow velocity belongs to the set flow velocity interval, if not, the velocity measuring tube is blocked.

4. The device for measuring air volume at the inlet of a coal mill in a pulverizing system according to claim 1, characterized in that: A plurality of flow equalizing grilles are fixed inside the air flow equalizer along the length direction of the air flow equalizer; the flow equalizing grilles are mesh structures and are used to equalize the air transmitted by the first air duct to obtain air with uniform flow.

5. The device for measuring air volume at the coal mill inlet of a pulverizing system according to claim 4, characterized in that: The flow balancing grid is a flow balancing grid made of carbon steel material.

6. The device for measuring air volume at the coal mill inlet of a pulverizing system according to claim 3, characterized in that: The first air duct is connected to the air flow equalizer through bolts, and the air flow equalizer is connected to the second air duct through bolts.

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