The power plant system is one of the most complex systems recognized in the world so far. In order to ensure the safe and stable production and operation of the power plant, the key core lies in the efficient and stable operation of the boiler, and the temperature field change in the boiler can be used as one of the key indicators of the boiler operation state.

At present, the temperature in the boiler of power plant can only be judged by the regular measurement of some monitoring points in the boiler, combined with the operation experience to judge the combustion of the whole boiler, the lack of real-time and accurate temperature field measurement system in the boiler. With the transformation of the global energy structure and the deep reform of the power market, the intelligent construction of power plants has become an urgent demand for the industry, but also the need for real-time and accurate collection of temperature data in the boiler, and then the relevant temperature information and combustion through the DCS feedback to the control system of the power plant, and finally achieve the wisdom of the power plant, digital upgrade.

After years of joint research and development by the expert team of Beijing Allinbyy and the College of Energy Power and Mechanical Engineering of North China Electric Power University, the acoustic-based furnace temperature measurement solution has been able to reflect the temperature field distribution in the furnace in real time and intuitively. This solution is the first in China, completely domestic, and achieved 100% autonomy and control, breaking the technological monopoly of international companies in China. The performance and index of this system exceed that of similar international products.

01.The basic principle of acoustic temperature measurement

The principle of acoustic temperature measurement is based on the relationship between sound velocity and the temperature of the medium. Taking the  acoustic temperature measurement model of a single-path furnace as an example, multiple groups of acoustic transmitting and receiving devices are arranged on the furnace wall around the section of the furnace, and the multi-path temperature is obtained by successively sounding. The two-dimensional temperature field distribution of the temperature measurement plane can be obtained by using CT reconstruction technology. As shown in the picture:

02.Acoustic temperature measurement solution architecture and functions

（1）Sonic transceiver system

Acoustic wave generator unit: acoustic wave generator is an energy conversion device, is an important part of the system. The relevant parameters of the work must be adjusted according to the specific situation of the boiler in order to achieve the optimization of the working state, the system uses a special electric sound source.ficial to acoustic impedance matching.

Acoustic wave receiver: The sensor is used to receive the audio signal from the acoustic wave transmitter, select the enhanced piezoelectric acoustic wave sensor, the frequency response, ambient temperature, electromagnetic interference has certain requirements, the system uses electret microphone.

Furnace measuring point unit: acoustic waveguide connecting acoustic generator and furnace body. The sound waves modulated by the acoustic generator are amplified here and fed into the furnace. On the one hand, it is used to weaken heat conduction and play a protective role. On the other hand, a reasonable acoustic waveguide is beneficial to acoustic impedance matching.

（2）Central processing control unit

The processing control unit is the core of the whole temperature measuring system. It implements all control, processing, input and output, and data storage.

（3）Visual operation management platform

The system provides a friendly man-machine interface, which can display flame deviation, isotherm diagram, online temperature monitoring, temperature change curve, etc., provides rich visual information for boiler combustion, and supports expansion and customization.

03.Advantages of acoustic temperature measurement solutions

. High accuracy, accuracy <1% (path temperature), temperature resolution at room temperature is 0.1℃, temperature resolution at hot state is 3℃. Not affected by uncertain factors such as radiation;

. Wide temperature range, can be used in the full load range of -100℃ ~ 2500℃ boiler;；

. The measurement space is not limited, not only can measure the average temperature, but also can determine the furnace temperature field distribution；

. High measurement sensitivity, real-time online monitoring；

. Visual interface, can present furnace section combustion intensity, flame eccentricity coefficient, isotherm diagram, temperature cloud map, path temperature historical change curve and other ways, the data is intuitive;；

. Independent system, can avoid conflicts with other systems, the use of high temperature sensor, while the system has a sound source self-test system, fault direct alarm, reduce daily maintenance workload;；

. Power plant operators can adjust the pulverized coal or air distribution in the boiler accordingly, and can also be connected with auxiliary systems such as targeted air distribution through the DCS system to achieve automatic adjustment of the combustion state of the boiler.

04.Project income

. The unit load climbing rate is increased by more than 0.5%, and the boiler depth peak load is reduced by more than 5%；

（2）Economic benefit

. Avoid pipe explosion accidents, unexpected shutdown loss of power generation 15000MWh；

（3）Social benefit