Patent ID: 7373258

Claim:
A method for monitoring and regulating a reactor for selective hydrogenation of an olefinic gasoline fraction feedstock containing a conjugated diolefin content, said feedstock flowing at a measured rate into said reactor, said method comprising adjusting the temperature of the reactor and hydrogen input to the reactor in response to maleic anhydride value (MAV) from samples taken at the input and the output of the reactor obtained by conducting the following sequence of stages: Withdrawing a sample at the input and at the output of said reactor at a determined frequency, Analyzing samples by their near infrared (NIR) spectrum by absorption at a wavelength range of between 800 nm and 2500 nm, Determining the maleic anhydride value (MAV NIR ) by near infrared values of the input and output samples determined by a treatment of the NIR spectra using a calibration base and a specific treatment, Determining from the MAV NIR of the input sample and the flow rate of the feedstock the amount of hydrogen to be introduced into the reactor that is used as a set point value in a first regulation loop of said value of the MAV NIR as input, Determining an optimum input temperature in the reactor that is used as a set point value in a second regulation loop of said value of the MAV NIR as output is determined from the MAV NIR of the output sample and a dynamic model, and in which the determination of MAV of each sample i of a series is conducted by a subtraction of spectra (delta method), characterized by the following sequence of operations: A series of samples is taken at the input or the output of the reactor for selective hydrogenation at a determined frequency, A reference sample is selected from an intermediate sample in the series of samples for which the MAV is determined chemically, The NIR spectra of each sample i of the series are obtained, The spectrum difference is formed between the spectrum of each sample i and the spectrum of the reference sample, The delta MAV of each sample is derived from the spectrum difference of said sample i with the spectrum of the reference sample by using correlation that is obtained from the calibration base, The MAV of sample i is obtained from the delta MAV of the sample i and the MAV of the reference sample.