Fiber Bragg gratings for temperature monitoring in methanol and methane steam reformers
Date
2017-10-04
Authors
Trudel, Elizabeth
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Abstract
Steam reforming of methanol and hydrocarbon are currently the processes of choice to produce hydrogen. Due to the endothermic nature of these reactions, zones of low temperature are commonly found in reformers. These zones can potentially damage the reformer through thermal stresses. Moreover, the response time and size of a reformer are controlled by the heat available to the reaction. The objective of this thesis is to demonstrate the feasibility of using fiber Bragg gratings as an alternative solution for temperature monitoring in methanol and methane steam reformers. To meet this objective, a sensor array containing seven gratings is placed in a metal-plate test reformer. First, temperature monitoring during methanol steam reforming is conducted in 12 different sets of conditions. The resulting profile of the temperature change along the length of the catalyst captures the zones of low temperature caused by the endothermic nature of the reaction. Several small changes in the temperature profile caused by increasing temperature and/or flow rates were captured, demonstrating the ability to use these gratings in methanol steam reforming. Similar experimental work was conducted to validate the possibility of using fiber Bragg gratings as temperature sensors in methane reforming. Using a regenerated grating array, data was collected for 13 operating conditions. The conclusions arising from this work are similar to those drawn from the methanol steam reforming work. The regenerated FBGs exhibited a behaviour that has not been reported in the literature which is referred to in this thesis as secondary erasure. This behaviour caused some instability in the grating signal and erroneous readings for some operating conditions. Despite this, the grating measurements captured the zones of low temperatures in the reformer and the small changes brought about by increasing the reforming temperature and lowering the steam to carbon ratio.
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Keywords
steam reforming, instrumentation, fiber optic sensors