Method for monitoring feeds to catalytic cracking units by near-infrared spectroscopy

Abstract

A monitoring of catalytic cracking processing is provided which uses near infrared (NIR) analysis to characterize cracking feeds, intermediates and products for chemical and physical properties such as saturates, monoaromatics, diaromatics, triaromatics, tetraaromatics, polar aromatics, total aromatics, thiophenes, distillation points, basic nitrogen, total nitrogen, API gravity, total sulfur, MCRT and % coker gasoil and the resulting characterization thereof. The NIR results can be used in FCC simulation software to predict unit yields and qualities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an FCC unit comprising a reactor and a regenerator showing the control system of the present invention in place for operating that FCC unit.

FIG. 2 is a Table which shows samples, including hydrotreater charges and products and FCC feeds used to control on-line weight percents of each hydrocarbon class.

FIG. 3 is a plot showing FCC feed sulfur under different operating philosophies.

FIG. 4 is a graph of a catalyst cycle life curve.

FIG. 5 is a graph of an FCC feed upset showing high SO_X.

FIG. 6 is a table of a neural network for on-line control of SO_X emissions.

FIG. 7 is a graph of the use of NIR on FCC hydrotreating.

FIG. 8 is a graph showing NIR predicted results versus Lab results for % Coker Gas Oil.

FIGS. 9 and 10 are graphs showing typical monitoring plots for feedstock quality and product yields.

Claims

1. A process for analyzing catalytic cracking hydrocarbon feeds intermediates and products exhibiting absorption in the near infrared (NIR) region comprising: a) measuring absorbances of said feed, intermediates, or products using a spectrometer measuring absorbances at wavelengths within the range of about 780-4000 nm, and outputting an emitted signal indicative of said absorbance;b) subjecting the NIR spectrometer signal to a mathematical treatment (e.g., derivative, smooth, baseline correction) of the emitted signal.c) processing the emitted signal or the mathematical treatment using a defined model to determine the chemical or physical properties of feeds, intermediates or products and outputting a processed signal; andd) monitoring on-line in response to the processed signal, at least one parameter of the catalytic cracking feed, intermediate or product.

2. The process of claim 1 including the step of using NIR measuring to provide real time optimization of (RTO) FCC monitoring.

3. The process of claim 1 including the step of using NIR measuring to automatically monitor FCC processing conditions.

4. The process of claim 1 including the step of using NIR measuring to maximize FCC monitoring as feedstock parameter changes.

5. The process of claim 1 including the step of using NIR measuring of FCC feed rate, reactor temperature, feed preheat or feed pressure to optimize FCC product monitoring.

6. The process of claim 1 including the step of using NIR measuring of FCC feed parameters to monitor weight percent of each hydrocarbon class.

7. The process of claim 1 including the step of using NIR measuring to monitor on-line a multiplicity of parameters for FCC processing.

8. The process of claim 1 wherein said absorbances are measured at wavelengths within the range of about 780-2500 nm.

9. The process of claim 1 wherein said absorbances are measured at wavelengths within the range of 1100-2200 nm.

10. The process of claim 1 wherein said absorbance is measured in at least one wavelength and includes the steps of: a) periodically or continuously outputting a periodic or continuous signal indicative of the intensity of said absorbance in said wavelength, or wavelengths in said two or more bands or a combination of mathematical functions thereof, andb) mathematically converting said signal to an output signal indicative of the mathematical function.

11. The process of claim 1 wherein said feed, intermediate, or product are measured for content of at least one of monoaromatics, diaromatics, triaromatics, tetraaromatics, polar aromatics, total aromatics benzothiophenes, dibenzothiophenes, distillation points, basic nitrogen, total nitrogen, API gravity, total sulfur, MCRT and % coker gasoil.

12. The process of claim 1 wherein the catalytic cracking produces products having lower average molecular weight than the feed, by contacting the feed with catalyst in a contacting zone and recovering and separating the products exiting from the cracking zone.

13. The process of claim 1 wherein the parameter of catalytic cracking of step (c) is selected from the group consisting of temperature, throughput, pressure, hydrogen feed rate, catalyst, and oil ratio.

14. The process of claim 1 including the steps of: obtaining a first data set of NIR spectroscopic data samples by subjecting the feed, intermediates, or products to NIR spectroscopy;generating a second data set of NIR spectroscopic data samples by processing the first data set using a second technique; andidentifying a component of the feed by performing a NIR analysis on the second data set.

15. The process of claim 1 including the step of: mathematically converting the signal to an output signal indicative of the parameter.

16. The process of claim 15 including the steps of: periodically or continuously outputting a periodic or continuous signal indicative of the intensity of the NIR absorbance in the wavelength, or wavelengths in the two or more bands or a combination of mathematical functions thereof, andmathematically converting said signal to an output signal indicative of the mathematical function.

17. The process of claim 1 including the step of using the NIR results in FCC simulation software to predict unit yields and qualities.

18. The process of claim 14 which allows direct monitoring of the feedstock properties and effluent yields in real time to ensure product quality and processing targets are achieved.