- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Evolution of volatile cloud in pulverized coal combustion with high-speed digital inline holographic visualization
摘要： The coal devolatilization plays a significant role in the combustion of pulverized coal particles. The evolution of volatile cloud during devolatilization of pulverized coal particles (105–125 μm) is studied in a high-temperature flat-flame burner by combining high-speed photography with high-speed digital inline holography (DIH). By the high-speed holographic visualization, the evolution of volatile cloud of pulverized coal from volatile release to soot aggregation generation can be divided into four stages. Effects of coal type on volatile cloud evolution are investigated using three different coals, i.e., Shanxi bituminous coal, Ximeng lignite and Yinni lignite. The results show that both the Shanxi bituminous coal and Ximeng lignite produce soot aggregation during devolatilization, which is rarely observed for Yinni lignite. Moreover, Shanxi bituminous coal has a higher potential in soot cluster formation for its higher coal rank than Ximeng lignite. The high-speed reconstructed image sequences are analyzed to measure the velocity slip between the parent particle and volatile cloud. Compared with Shanxi bituminous coal, Ximeng lignite exhibits a larger slip velocity. This work also demonstrates that high-speed DIH has the powerful capacity of directly observing the evolution of volatile cloud, and helps to gain a deep understanding of pulverized coal combustion.
关键词： Volatile cloud,Coal combustion,High-speed digital inline holography,Soot aggregation,High-speed photography
更新于2025-09-23 15:22:29
-
Two dimensional temperature measurement characteristics in pulverized coal combustion field by computed tomography-tunable diode laser absorption spectroscopy
摘要： Two dimensional temperature and concentration distributions are important parameters for pulverized coal combustion used for power plant to understand the combustion field and develop the high efficient combustion technologies. However, it is difficult to measure two dimensional temperature and concentration in pulverized coal combustion field using conventional measurement technologies because pulverized coal combustion produces lots of dust and strong emission from its flame. This paper focused on the application of two dimensional temperature measurement method based on the combination of computed tomography and tunable diode laser absorption spectroscopy using absorption spectra of water vapor at 1388nm and 1343nm for each laser scanning using direct absorption spectroscopy, which show the better characteristics of spatial-temporal resolution, fast response, high sensitivity, self-calibration and optical accessibility. Accuracy of temperature measurement using tunable diode laser absorption spectroscopy was improved by applying the corrected spectroscopic database. Computed tomography reconstruction accuracy of 16 laser-paths configuration was evaluated using sum of squared difference (0.001) and zero-mean normalized cross-correlation (over 0.991), which presented the consistent temperature between assumed and reconstructed distributions. This developed computed tomography-tunable diode laser absorption spectroscopy was successfully applied to pulverized coal flame for two dimensional temperature measurement with 1 ms temporal resolution for time-series two dimensional temperature measurement in the range of 300K-2500K. The rationality was demonstrated by comparison of pulverized coal flame and Methane-Air flame temperature distributions due to the main heat release produced by methane fuel. Its applicability to pulverized coal combustion field will be benefit for optimal operation control and combustion efficiency improvement by combustion organization or new design of combustion system.
关键词： Power plant,Pulverized coal combustion,Computed tomography (CT),Tunable diode laser absorption spectroscopy (TDLAS),Two dimensional temperature measurement
更新于2025-09-23 15:21:01
-
Pulverized coal combustion application of laser-based temperature sensing system using computed tomography a?? Tunable diode laser absorption spectroscopy (CT-TDLAS)
摘要： The investigation of combustion phenomena in pulverized coal flames is significant for combustion optimization related to energy conservation and emission reduction. Real-time two dimensional (2D) temperature and concentration distributions play an important role for combustion analysis. The non-contact and fast response 2D temperature and concentration distribution measurement method was developed in this study. The method is based on a combination of computed tomography (CT) and tunable diode laser absorption spectroscopy (TDLAS). The accuracy evaluation of developed 32-path CT-TDLAS demonstrated its feasibility of 2D temperature measurement. 32-path CT-TDLAS was applied to CH4 and 5 kg/h coal combustion fields for 2D temperature measurement. The time-series 2D temperature distribution in coal combustion furnace was measured using 32-path CT-TDLAS measurement cell with kHz time resolution. The transient temperature field of combustion flame directly reflects the combustion mode and combustion stability. The measurement results demonstrate its applicability of CT-TDLAS to various types of combustor, especially the combustion fields with coal and ash particles. CT-TDLAS method with kHz response time enables the real-time 2D temperature measurement to be applicable for combustion analysis.
关键词： 2D temperature measurement,Computed tomography (CT),Tunable diode laser absorption spectroscopy (TDLAS),Time-series distribution,Coal combustion
更新于2025-09-23 15:19:57
-
Study on the oxidation and release of gases in spontaneous coal combustion using a dual-species sensor employing laser absorption spectroscopy
摘要： Coal spontaneous combustion (CSC) is a common hazard in coal mines and a significant reason for the loss of coal in stockpiles and mines. To investigate the oxidation and release of gas due to of CSC, a miniature purpose-built laser-based sensor system capable of precise gas measurement and data processing was configured. A distributed feedback (DFB) diode laser with a central wavelength of 2.33 μm, in conjunction with a Herriot-type cell and wavelength modulation spectroscopy (WMS), was used for the simultaneous detection of methane (CH4) and carbon monoxide (CO) during coal combustion. The second-harmonic of WMS was applied to ensure sensor robustness and sensitivity with long-term performance for the system being evaluated by calculating the Allan-Werle deviations for the concentrations of CH4 and CO. The limits of detection (LoDs) for CH4 and CO were 0.05 ppm based on integration times of 120 s and 70 s, respectively. The dual-species sensor was employed for real-time and in situ investigations of coal samples for temperatures ranging from 85 °C to 200 °C and was considered suitable for integration into field monitoring equipment, especially for online early warning forecasting applications in CSC.
关键词： Wavelength modulation spectroscopy,Spontaneous coal combustion,Chemical inhibitor,Laser-based dual-species sensor,Self-heating oxidation
更新于2025-09-12 10:27:22
-
Elemental mercury removal from flue gas over TiO2 catalyst in an internal-illuminated honeycomb photoreactor
摘要： TiO2 catalyst in an internal-illuminated honeycomb photoreactor was prepared for Hg0 removal from flue gas. The Hg0 removal efficiency was above 95% under the optimal operation condition. With the increasing TiO2 coating value, the Hg0 removal efficiency significantly increased. The catalyst calcined at 400 oC presented optimal Hg0 removal performance, while higher calcination temperature weakened the Hg0 photocatalytic removal activity. Similar Hg0 removal performances were obtained under UV irradiation when the reaction temperature was in the range of 25-90 oC, and 1.5 mW/cm2 of UV light irradiation was competent for Hg0 photocatalytic removal. With the same quantity utilization of TiO2 catalyst, the internal-illuminated honeycomb photoreactor presented better Hg0 removal performance than fixed-bed reactor. Finally, the procedure of Hg removal from flue gas over TiO2 catalyst in internal-illuminated honeycomb photoreactor was proposed, and the product in the Hg0 photocatalytic removal process was analyzed as well.
关键词： mercury,coal combustion,TiO2,photocatalytic removal,photoreactor
更新于2025-09-09 09:28:46