Catalytic Reforming (CR) process converts low-octane linear hydrocarbons into branched alkanes and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking.
The catalyst mostly contains platinum or rhenium on an alumina support base, after carbon burning(regeneration), that needs to be chlorinated to activate. If the catalyst is not chlorinated (or insufficiently chlorinated), the platinum in it would be reduced almost immediately to metallic state by hydrogen. By contrast, an excessive chlorination could depress significantly the activity of the catalyst.
Critical Control of Process Gas
Catalyst regeneration requests a continuous monitoring of oxygen(O2) concentration of the regenerator off-gas. If O2 is insufficient, the deposited coke may not completely combusted, while an excess O2 will cause over-temperature and reduce the life and activity of the catalyst.
Trace moisture(H2O) is required to monitor in circulating hydrogen to maintain optimal water-chloride balance for catalyst chlorination
Hydrogen(H2) purity of the circulating hydrogen is measured to determine dehydrogenation ratings and optimize reforming processes.
Challenge of Instrumentation
Sampling analyzers are traditionally used for monitoring process gases of catalytic reforming. The sampling probe and sampling line are vulnerable to particulates, corrosives and high temperature, resulting in massive maintenance, high cost and not a real continuous operation.. Besides, the extractive method is slow response that reduces its efficiency for process control.
The non-contact laser and sensor of the in-situ LGA combined with continuous purge results in virtually maintenance free, and performs well in the presence of corrosive gas like chlorine. High-speed response (down to 1s) highlights its reliability for process control. The extreme monochromaticity of laser spectrum ensures no interference with all other gas species.
The GRD analyzer is highly flexible to measure hydrogen purity in any content level with a compensation to minimize interference from other gases like CO, CO2, CH4.
PSA adsorption tower
PSA product gas
*The laser probes used for fired heaters measuring O2,CO are under construction.