Thermal expansion online monitoring system

Overview

Power plant facilities include lots of equipment made of steel, which would expand/contract when heated/cooled by water, flue gas, steam or air. Ignorance of thermal expansion movement may result in failure of boiler tubes, vessels, etc. The device to monitor boiler thermal expansion is basically expansion pointer. In boiler startup stage, inpection personnel have to check at site. When boiler is in normal operation, low frequency of human visual checking is not enough to find out abnormal expansion in time. As response to peak shaving policy, thermal power generation units have to regulate boiler load according to demands. Thermal expansion movements occur to boiler a lot.

For a large thermal power plant, monitoring by expansion pointer is out of date due to following reasons:

• Human visual checking can get only intermittent datas. It’s not continuous and in-time feedback.
• There is no history data curve for reference in analysis process.
• It can’t give alarm signal when restricted expansion happens. People can only get indication after long time.

Boiler thermal expansion monitoring system is an online solution based on computer vision. It is designed to monitor expansion movement of boiler, steam pipe, steam turbine casing in X, Y, Z directions.

Principle

Stereo camera works on the same principle of human eyes, which can tell object distance based on optical parallax. Dual cameras takes photos of checkerboard at the same time. By calculation of optical parallax of two photos, computer can get expansion movement in X, Y, Z directions. During working, stereo cameras fixed on platform observe the movement of checkerboard attached on boiler components. Finally thermal expansion monitoring system will display the result on computer of DCS for operation people.

Features

• Binocular vision, high precision up to 0.2mm within 100mm range.
• No drift in measurement result.
• High speed in-time calculation. No need for calibration. Reliable result.
• Easy installation, wide application.

Applications

Thermal expansion online monitoring system can be used to watch out expansion movement of large steam pipeline, steam turbine casing, boiler drum, header, etc.