CN107631766A - The online purging system of volume measuring pipe in the Chinese mound of air channel of thermal power plant - Google Patents

Abstract

The invention discloses an online purging system of a Venturi air volume measuring tube in a primary air duct of a thermal power plant, which solves the problems of heavy workload and easy occurrence of burn accidents in the dust cleaning of the Venturi measuring tube. A compressed air inlet pipe (6) is arranged on the inner wall of the primary air inlet pipe (1) above the front side of the air inlet of the Venturi measuring tube (3), and the central axis of the compressed air inlet pipe (6) is aligned with the The central axis of the primary air inlet pipe (1) is arranged perpendicular to each other; the lower end of the compressed air inlet pipe (6) is connected with a purge nozzle pipe (7), and the central axis of the purge nozzle pipe (7) is aligned with the primary air inlet pipe (6). The included angle of the central axis of the air inlet pipe (1) is 45°; the compressed air inlet pipe (6) extending outside the primary air inlet pipe (1) is provided with a compressed air shut-off valve (8), A compressed air input pipeline (9) is connected to the upper end of the compressed air inlet pipe (6). To ensure the accuracy of Venturi tube measurement and the safety of production.

Description

On-line purge system of Venturi air flow measuring tube in primary air duct of thermal power plant

technical field

The invention relates to a purging system of an air volume measuring device in a boiler air duct of a thermal power plant, in particular to an online purging system of a Venturi measuring tube used for measuring air volume in a primary air duct or a secondary air duct of a thermal power plant boiler.

Background technique

At present, primary air passages and secondary air passages are provided on boilers of thermal power plants to provide air volume for boiler combustion. In order to control the air volume of the boiler and improve the combustion efficiency of the boiler, an air volume measuring device is generally installed in the air duct. The air flow measurement device is composed of a differential pressure measuring tube and a differential pressure transmitter; there are many types of differential pressure measuring tubes, among which the Venturi measuring tube is more commonly used. The Venturi measuring tube can measure the dynamic pressure of the gas flow through the tube through its unique variable diameter section, so as to calculate the flow rate of the gas. The primary and secondary air entering the boiler needs to be heated by the air preheater first, and then blown into the boiler through the primary and secondary air pipes. Since the air preheater is preheated with dusty flue gas, during the preheating process, the dust in the flue gas will adhere to the heat exchange fins, and when the air supplying the boiler passes through the preheater, it will The dust attached to the heat exchange fins is brought into the primary and secondary air intake pipes. Part of the dust brought in will adhere to the Venturi measuring tube, thereby changing the variable diameter section of the Venturi measuring tube and seriously affecting the accuracy of air flow measurement. In order to overcome this defect, the existing method is generally to remove the differential pressure transmitter, blow high-pressure gas into the Venturi measuring tube outside the interface of the differential pressure transmitter, and purge and clean the dust accumulated inside the Venturi tube. In this method, the workload of disassembling the differential pressure transmitter is large, and the interruption measurement time of the air volume is long, especially because the air temperature in the primary air duct is as high as 270°C, and it is easy to blow from the interface of the differential pressure transmitter to the outside of the air duct, resulting in Personnel burn accident.

Contents of the invention

The invention provides an online purging system for a Venturi air volume measuring tube in a primary air duct of a thermal power plant, which solves the problems of heavy workload and easy occurrence of burn accidents in the dust cleaning of the Venturi measuring tube.

The present invention solves the above technical problems through the following technical solutions:

An on-line purging system for Venturi air volume measuring tubes in a primary air duct of a thermal power plant, including a primary air inlet duct, a Venturi measuring tube support frame is arranged in the primary air intake duct, and a Venturi measuring tube support frame is installed on the venturi measuring tube support frame A Venturi measuring tube is fixedly installed, and the central axis of the Venturi measuring tube and the central axis of the primary air inlet duct are set parallel to each other. There is a differential pressure tube connected between the tube and the differential pressure transmitter, and a compressed air inlet tube is arranged on the inner wall of the primary air inlet tube above the front side of the air inlet of the Venturi measuring tube. The central axis and the central axis of the primary air inlet pipe are arranged perpendicular to each other; the lower end of the compressed air inlet pipe is connected with a purge nozzle pipe, and the center axis of the purge nozzle pipe and the central axis of the primary air inlet pipe are clamped The angle is 45 degrees; a compressed air shut-off valve is set on the compressed air inlet pipe extending out of the primary air inlet pipe, and a compressed air input pipeline is connected to the upper end of the compressed air inlet pipe.

The vertical distance between the central point of the lower end of the purge nozzle pipe and the central axis of the Venturi measuring tube is 0.5 meters, and the horizontal distance between the central axis of the compressed air inlet pipe and the longitudinal section of the air inlet of the Venturi measuring tube is 0.5 meters; The air pressure in the compressed air input pipeline is 50 times of the wind pressure in the primary air inlet duct.

According to the invention, high-pressure compressed air regularly purges the dust accumulation inside the Venturi nozzle, thereby ensuring the accuracy of Venturi tube measurement and ensuring safe and smooth production.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

An on-line purging system for Venturi air flow measuring tubes in a primary air duct of a thermal power plant, comprising a primary air inlet duct 1, a Venturi measuring tube support frame 2 is arranged in the primary air inlet duct 1, and a venturi measuring tube support frame 2 is arranged in the Venturi measuring tube A Venturi measuring tube 3 is fixedly installed on the support frame 2. The central axis of the Venturi measuring tube 3 and the central axis of the primary air inlet duct 1 are arranged parallel to each other. Transmitter 5, a differential pressure tube 4 is connected between the Venturi measuring tube 3 and the differential pressure transmitter 5, on the inner wall of the primary air inlet tube 1 above the front side of the air inlet of the Venturi measuring tube 3 A compressed air inlet pipe 6 is provided, and the central axis of the compressed air inlet pipe 6 and the central axis of the primary air inlet pipe 1 are arranged perpendicular to each other; the lower end of the compressed air inlet pipe 6 is connected with a purge nozzle pipe 7 , the included angle between the central axis of the purge nozzle pipe 7 and the central axis of the primary air intake pipe 1 is 45°; the compressed air intake pipe 6 extending out of the primary air intake pipe 1 is provided with a compressed air shut-off The valve 8 is connected with a compressed air input pipeline 9 at the upper end of the compressed air inlet pipe 6 .

The vertical distance between the center point of the lower end of the purge nozzle pipe 7 and the central axis of the Venturi measuring tube 3 is 0.5 meters, and the horizontal distance between the central axis of the compressed air inlet pipe 6 and the longitudinal section of the air inlet of the Venturi measuring tube 3 is 0.5 meters. In order not to affect the shape of the inlet flow field of the Venturi measuring tube 3, the distance between the central axis of the compressed air inlet tube 6 and the air inlet section of the Venturi measuring tube 3 should not be too close. After many tests, it was found that 0.5 meters is suitable. In order to ensure the purging effect, the air pressure in the compressed air input pipeline 9 must be greater than or equal to 50 times the wind pressure in the primary air inlet pipe 1 . During the field test, the compressed air shut-off valve 8 should be opened in time according to the change of the flow meter for purging, and the purging time is usually 2 minutes.

Claims (2)

1. the online purging system of volume measuring pipe in a kind of Chinese mound of air channel of thermal power plant, including primary air intake pipe（1）, In primary air intake pipe（1）In be provided with Venturi meter support frame（2）, in Venturi meter support frame（2）Upper fixation It is provided with Venturi meter（3）, Venturi meter（3）Axis and primary air intake pipe（1）Axis be each other It is arranged in parallel, in primary air intake pipe（1）Outside be provided with differential pressure transmitter（5）, in Venturi meter（3）With differential pressure Transmitter（5）Between be connected with differential pressure pipe（4）, it is characterised in that in Venturi meter（3）Air intake vent front side top one Secondary wind blast pipe（1）Madial wall on be provided with compressed air blast pipe（6）, compressed air blast pipe（6）Axis and one Secondary wind blast pipe（1）Axis be arranged substantially perpendicular to each other；In compressed air blast pipe（6）Lower end be connected with purging shower nozzle Pipe（7）, purge shower head pipe（7）Axis and primary air intake pipe（1）The angle of axis be 45 °；Reach First air Blast pipe（1）Outside compressed air blast pipe（6）On be provided with compressed air shut-off valve（8）, in compressed air blast pipe（6） Upper end be connected with compressed air intake line（9）.

2. the online purging system of volume measuring pipe in the Chinese mound of air channel of thermal power plant according to claim 1, it is special Sign is, purges shower head pipe（7）The central point and Venturi meter of the lower end mouth of pipe（3）Axis vertical range be 0.5 Rice, compressed air blast pipe（6）Axis and Venturi meter（3）Air inlet longitudinal cross-section horizontal range be 0.5 Rice；Compressed air intake line（9）In air pressure be primary air intake pipe（1）50 times of middle blast.