Measurement device for air volume and smoke volume

1、 Overview:

The straight sections of the main air and flue gas pipelines in most power plant boilers are relatively short, and the flue gas pipelines are severely worn, corroded, and clogged. In order to solve this problem, the Thermal Research Institute conducted actual measurements of the pipelines on site based on different boiler conditions. Using measurement methods such as double Venturi and array, measurement devices were designed and installed, achieving good results.

2、 BS-6D Dual Venturi Airflow Measurement Device:

The dual Venturi airflow measurement device is used for accurate measurement of primary and secondary airflow, as well as the inlet airflow of the air supply fan. The product has a compact structure, easy installation, and stable and accurate measurement results. It has been successfully applied in many domestic power plants, laying a good foundation for improving their boiler operation level and automatic operation.

a. Working principle

The dual Venturi air flow measurement device consists of two sets of Venturi tubes, one inside and one outside. It is made based on the principle that the airflow velocity increases at the throat of the Venturi tube and the static pressure decreases. The device measures the static pressure by opening holes inside the inner Venturi tube and outside the outer Venturi tube. After two-stage Venturi amplification, the actual dynamic pressure of the air duct is amplified by about 10-20 times. By adjusting the cross-sectional contraction ratio of the Venturi tube appropriately, the pressure difference and sensitivity measured by the device can be changed. According to the structure and size of the air duct, usually 2-5 sets of dual Venturi wind measuring devices are installed in each air duct, and then the signal is led to the transmitter after passing through the pressure equalization box. Our institute will calibrate the dual Venturi wind measurement device on site before it is installed and put into use.

  b. Technical features

(1) Under the same measurement conditions, it can generate a large pressure difference signal, stable output signal, and relatively small relative error;

(2) The pressure loss is relatively small, which does not affect the air duct flow field or the effective pressure head of the fan;

(3) Low working conditions are required, and the length of the straight pipe section in front of the device is not high;

(4) Easy installation, safe and reliable operation, and low maintenance workload;

(5) There are no special requirements for the shape and structure of the pipeline, and both circular and rectangular pipelines can be installed.

  3、 Array flow measurement device:

Most of the straight sections of the secondary and main air ducts in power plant boilers cannot meet the measurement requirements, and the air duct section is large, resulting in uneven distribution of flow velocity on the section. In order to ensure measurement accuracy, multiple multi air volume measuring devices can be arranged with equal sections, and the positive pressure and negative pressure of each measuring device can be connected to each other. Finally, a set of signals is led out to the transmitter. This multi-point combined air volume measuring device is called an array type air volume measuring device, which does not have many requirements for the straight section of the air duct. Generally, only the length of the straight section is not less than the equivalent diameter of the pipeline to design the measuring device. The array type air volume measurement device can be used for total air volume measurement, secondary air volume measurement, powder production system air volume measurement, etc. According to the requirements of pipeline size, structure, and measurement medium, four different types of array air volume measurement devices can be designed:

a、 Standard array type air flow measurement device - a standard measurement device designed with a flow coefficient of 1 using the principle of specific tube;

b、 Uniform velocity array air flow measurement device - using an array of uniform velocity tubes, adept at measuring air flow in short straight pipe sections;

c、 Anti blocking backrest type array air flow measuring device - with good anti blocking performance, suitable for measuring airflow with dust, and widely used.

d、 Multi point dual Venturi airflow measurement device - with good anti blocking performance and high measurement accuracy, suitable for measuring airflow with dust.

4、 Airflow measurement design and service:

What air volume measurement requires is not a simple product, but a complete solution. From system design, installation to calibration and debugging, every step must have specialized technology, qualifications, and experience. Xi'an Thermal Power Research Institute has strong technical strength and has designed and manufactured a large number of various air flow measurement devices for power plants over the years. It also provides technical support and services for cold state testing and air flow calibration of power plant boilers, which has gained the trust of users.

 

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