Primary air speed measuring device

JN-FS Primary Air Velocity Measuring Device

1、 Product Overview

With the continuous increase in the capacity of power generation units, the length of the pulverized coal feeding pipeline in the pulverizing system, which is one of the main auxiliary systems of coal-fired boilers, has also greatly increased, and the resistance difference of each pulverized coal feeding pipeline has also increased, resulting in problems such as pulverized coal accumulation in the pipeline, uneven primary air flow into the boiler, and pulverized coal pipe blockage. The stability and economy of boiler combustion in coal-fired power plants are closely related to the wind speed of primary air entering the furnace and the size and uniformity of pulverized coal concentration. The level of pulverized coal concentration and the uniformity of air and powder in each pulverized coal burner directly affect the stability of combustion conditions in the furnace and the combustion efficiency of the boiler.

At present, a lot of experimental research work has been done on the online monitoring method of air and dust in power plant boilers in China, and many measurement schemes have been proposed in order to find a more ideal measurement method. According to the actual situation, our company has developed a JN-FS primary air speed and air volume monitoring device to accurately measure the primary air speed, and reasonably adjust the matching ratio of primary, secondary, and tertiary air volumes as well as the air volumes of the upper, middle, and lower layers of secondary air based on different coal types, burner types, boiler loads, and other factors, so as to achieve optimal combustion of power plant boilers.

2、 Measurement principle

Based on the principle of Pitot tube differential pressure measurement, the system is installed on a pipe with its probe inserted into the pipe. When there is air flow in the pipe, the windward side is impacted by the air flow, where the kinetic energy of the air flow is converted into pressure. The pressure in the windward side of the pipe is relatively high, and its pressure is called "full pressure"; Due to the fact that the leeward side is not impacted by airflow, the pressure inside the duct is the static pressure inside the duct, which is called "static pressure". The difference between total pressure and static pressure is called differential pressure, and its magnitude is related to the wind speed inside the duct. The greater the wind speed, the greater the differential pressure; The lower the wind speed, the smaller the differential pressure. By accurately measuring the magnitude of the differential pressure and finding the corresponding relationship between the differential pressure and the wind speed, the wind speed in the pipe can be accurately measured.

3、 System composition

The JN-FS primary air velocity measurement system is mainly composed of self cleaning and anti clogging primary measurement elements, pressure pipes, differential pressure transmitters, etc. The measuring device converts the wind speed in the air duct into a differential pressure, which is connected to a differential pressure transmitter through a pressure conduit. The differential pressure transmitter outputs a 4-20mA current signal and is directly connected to the DCS system for configuration. If the system is not connected, a secondary meter can be provided.

4、 System characteristics

1. Wear resistance: The probe of the primary measuring element is made of wear-resistant ceramic, sintered at a high temperature of 1850 ℃, and can be used for more than five years;

2. Anti clogging: A self cleaning device is added to the primary measuring element to prevent clogging and eliminate the need to install an air source for purging.

3. High measurement accuracy. It has high measurement accuracy (system error ≤ 1.5%), good repeatability, and high reliability in use.

4. Energy saving. The pulverized coal flow rate and flow measurement device has small resistance and small pressure loss.

5. Easy installation. The plug-in installation method, flange structure, installation and maintenance are relatively simple.