Automatic temperature measurement system

Non-contact fully automatic continuous temperature measurement technology for coke ovens Ning Fangqing (Anhui University of Technology, Ma’anshan 243002), Zhou Yaping, Gu Shubo, Wang Kaibao, Wang Haiyan, Qian Hulin, Song Qianshun (Magang Coal Coking Company, Ma’anshan 243021). Measuring the temperature of the flame channel is an important part of the daily operations in coke oven production; operators use optical pyrometers or infrared thermometers to measure the surface temperature of the bricks at the bottom of the flame channel, with inspections being carried out every 4 hours. During manual measurements, errors can be quite large due to factors such as the temperature measurement time, the location where the temperature is measured, the skill level of the person performing the measurement, and external weather conditions; these errors are generally within the range of ±(7～15)°C. The “non-contact, fully automatic continuous temperature measurement system for coke ovens,” developed over a period of 3 years through joint efforts by Anhui University of Technology, Magang Coking Company and other organizations, provides an excellent solution for measuring the temperature of coke ovens. 1 Principle of temperature measurement: All objects with a certain temperature continuously emit infrared radiation energy into the surrounding space, and the amount of infrared radiation energy emitted by an object is closely related to its surface temperature. Therefore, by measuring the object’s own infrared radiation energy, its surface temperature can be accurately determined. The intensity distribution of infrared radiation emitted by an object into the surrounding space (see Figure 1) is given by: where C is the speed of light ； h is the Planck constant ； k is the Boltzmann constant ； T is the absolute temperature ； Entry as light wave wavelength ； ε is the blackness coefficient (emissivity). The emissivity (ε) of an object has a significant impact on the intensity of infrared radiation. In real objects found in nature, the vast majority are not black bodies (ε=1), but rather gray bodies. Therefore, the radiation intensity of a real object depends not only on the wavelength of the radiation and the surface temperature of the object, but also on factors such as the type of material comprising the object, its surface condition, and environmental conditions. Its emissivity indicates the degree to which the thermal radiation intensity of the real object resembles that of a black body, with values ranging from 0 to 1. According to the radiation law, if the emissivity of a material is known, the infrared radiation properties of that object can be determined. Figure 1: Infrared radiation distribution of an object. Figure 2: Schematic diagram of the infrared temperature measurement system. 2. Composition of the infrared temperature measurement system: The infrared temperature measurement system consists of an optical system, optical fibers, a signal processing system (instrument), and a protection system, as shown in Figure 2. The optical system is primarily designed to capture the infrared radiation from the surface of the nose brick at the bottom of the vertical flue, focus this infrared radiation on the optical fiber, and then transmit it to the photosensitive detector. The signal processing system can convert the received infrared radiation energy into corresponding temperature signals based on the laws of infrared radiation. (1) Optical system. The optical system is directly mounted on the small lid of the viewing hole at the top of the furnace; it is aimed visually at the surface of the nose brick. The optical resolution of this system is 150:1. For JN50-type coke ovens, the size of the measured light spot is approximately 45 mm, which is less than 50% of the area of the nose brick ； The maximum temperature tolerance of the optical system is 250°C. The surface temperature on the small lid of the viewing port generally varies between 100 and 200°C; through air cooling, this temperature can usually be kept around 80–100°C, ensuring the long-term stable operation of the optical system ； The total height of the optical system is less than 130 mm. (2) Protection system. By protecting the optical system from dust and providing cooling, the effects of high temperatures, dust, and heat can be effectively prevented. Additionally, the entire optical system features a fully sealed design, preventing dust, rainwater, and high-temperature steam from entering its interior. (3) Optical fiber (fiber optic). It transmits the optical signal from the optical system to the photosensitive detector; the optical fiber used is an infrared quartz fiber. The chemical composition of quartz material is SiO2, and it possesses excellent physicochemical properties, including corrosion resistance and a high melting point. (4) Signal processing system (instrument). It converts optical signals into temperature signals; its operating temperature is below 60°C. This unit typically features a double-shell design, with compressed air used for cooling in between, while the signal processing system (instrument) is placed on a platform inside the furnace. 3 Installation of the system: MaSteel’s JN50 type coke ovens have 65 carbonization chambers and 66 combustion chambers. The current temperature measurement channels are the 7th channel on the machine side and the 21st channel on the coke side. The coke pushing sequence is 5-2; therefore, the 8th channel on the machine side and the 20th channel on the coke side, which are located near the rails, were selected. Ten representative combustion chambers were chosen from each of the machine side and the coke side. The gas supply pipes and fiber optic cables are installed along the bottom of the coal loading car tracks, without interfering with normal production operations or roof cleaning. 4 Comparison with temperature measurement in Shift 3: The fully automatic continuous infrared temperature measurement system for coke ovens uses the same temperature measurement points as the current manual method, namely the nose brick at the bottom of the vertical flame channel of the coke oven ； In the fully automatic continuous infrared temperature measurement system for coke ovens, temperature monitoring is carried out continuously, whereas in the case of manual temperature measurement, the readings are taken 5 minutes after the downward airflow has changed. For manual temperature measurement, the monitoring points include all furnaces numbered 1 to 65 in the 7th channel on the machine side, as well as all furnaces numbered 1 to 65 in the 21st channel on the coke side. In contrast, the fully automatic continuous temperature measurement system uses 10 representative furnaces in the 8th channel on the machine side and 10 representative furnaces in the 20th channel on the coke side for monitoring purposes. Figure 3a shows a comparison with manual temperature measurement; Figure 3b also presents a comparison with manual temperature measurement. Figure 3a compares the two temperature measurement methods (using the machine side as an example, with data from 20061201 to 20061224 over a consecutive 24-day period). To facilitate comparison with manual temperature measurement, data taken 5 minutes after the downward airflow exchange was considered. It can be seen from the temperature trend curves of both groups that the trends in temperatures measured by the two methods are generally similar. However, manual temperature measurement is greatly affected by human factors, resulting in larger fluctuations in the obtained temperature data. By calculating the statistical average of the two sets of data, it was found that the non-contact, fully automatic continuous temperature measurement method for coke ovens yields a temperature 23.6°C lower than that obtained through manual measurement. If the deviation is corrected for the fully automatic continuous temperature measurement data of the coke oven, the trend curve shown in Figure 3b is obtained, and the curves derived from the two sets of data are essentially identical. 5 Reliability analysis (1) The optical lens is installed on the small furnace lid, and the main influencing factors are dust and high temperatures. The optical lens features a fully sealed design; a dust protection cover is installed at the front end of the lens, and a slight positive pressure is maintained using compressed gas to prevent dust from entering. Based on the continuous operation results at the site, the optical lens is very clean. (2) The optical fibers are placed inside galvanized pipes and fixed on the outside of the coal car track bed. Under normal conditions, the temperature ranges from 50 to 80°C; in situations where graphite is being burned or under other similar conditions, the flame cannot reach the galvanized pipes directly, and the system is currently operating properly. (3) The design temperature for the instrument (signal processing unit) is 0–60°C, while the instrument is installed on the furnace platform, where the temperature does not exceed 50°C. (4) Optical lenses and optical fibers are made of inorganic materials such as glass and quartz, so there is no issue of aging; therefore, the service life of the contactless, fully automatic continuous temperature measurement system for coke ovens is very long, generally more than three times that of thermocouples. 6 Conclusions (1) The temperature measurement points of the contactless, fully automatic, continuous temperature measurement system for coke ovens are exactly the same as those of the current three-shift temperature measurement method, and its temperature measurement accuracy is higher than that of the current method. (2) The temperature measurement process is fully automated; the data from the temperature measurement system can be directly fed into the computer control system, which then enables automatic control of the furnace heating, reduces fluctuations in furnace temperature, and stabilizes the quality of coke. (3) This project has been granted a **patent** with the patent number ZL200620071265.1; the feature of this patent is that an infrared thermometer or optical system is installed above the viewing hole or the small lid of the coke oven.

Could the moderator also upload the images? My article is in PDF format, and it’s not possible to upload it here. 2# I’m awesome

How much is the investment roughly, and what are the maintenance costs?

Is it used by other manufacturers besides Magang?