Tunable Diode Laser Sensor for Monitoring and Control of Harsh Combustion Environments

VonDrasek, William ; Melsio-Pubill, Anna

American Air Liquide

关键词: Fiber Optics;    Aluminium;    Combustion;    Optical Sensors, Tdl, Tunable Diode Lasers, Eaf, Off-Gas Monitoring, Reheat Furnace, Reverberatory Furnace, Process Control, Combustion Monitoring, O2, Co, H2O, And Temperature Monitoring, Multiple Species Sensor;    Monitoring;   

DOI  :  10.2172/882872
RP-ID  :  DOE/CH/11030
RP-ID  :  FC36-00CH11030
RP-ID  :  882872

美国|英语

来源: UNT Digital Library

【 摘 要 】

This work represents the collaborative effort between American Air Liquide and Physical Sciences, Inc. for developing a sensor based on near-IR tunable diode lasers (TDL). The multi-species capability of the sensor for simultaneous monitoring of CO, O2, and H2O concentration as well as gas temperature is ideal for in-situ monitoring on industrial furnaces. The chemical species targeted are fundamental for controlling the combustion space for improved energy efficiency, reduced pollutants, and improved product quality, when coupling the measurement to a combustion control system. Several add-on modules developed provide flexibility in the system configuration for handling different process monitoring applications. For example, the on-Demand Power Control system for the 1.5 ?m laser is used for high particle density exhaust streams where laser transmission is problematic. For long-distance signal collection a fiber optic communication system is used to reduce noise pick-up. Finally, hardened modules to withstand high ambient temperatures, immune to EMF interference, protection from flying debris, and interfaced with pathlength control laser beam shielding probes were developed specifically for EAF process monitoring. Demonstration of these different system configurations was conducted on Charter Steel's reheat furnace, Imco Recycling, Inc. (now Aleris International, Inc.) aluminum reverberatory furnace, and Gerdau Ameristeel's EAF. Measurements on the reheat furnace demonstrated zone monitoring with the measurement performed close to the steel billet. Results from the aluminum furnace showed the benefit of measuring in-situ near the bath. In this case, low-level furnace optimization was performed and demonstrated 5% fuel savings. Monitoring tests on the EAF off-gas demonstrated the level of industrialization of the sensor to survive the harsh EAF environment. Long-term testing on the EAF has been on-going for over 6 months with essentially zero maintenance. Validation of the TDL measurement on the EAF was confirmed by comparison with extractive sampling CO measurements.