Monitoring the activity of reforming catalyst

Patent metadata

Field	Value
Publication number	US-9945801-B1
Application number	US-201615293653-A
Country	US
Kind code	B1
Filing date	Oct 14, 2016
Priority date	Oct 14, 2016
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A method and system for determining changes in the catalytic activity of reforming catalyst where an outlet temperature of the catalytic reactor is measured and a temperature approach to equilibrium calculated based on the measured outlet temperature. The temperature approach to equilibrium is compared to an empirical model-based temperature approach to equilibrium calculated for the same operating conditions, the comparison showing changes in the catalytic activity of the reforming catalyst.

First claim

We claim:

1. A method for determining changes in the catalytic activity of reforming catalyst, the method comprising:
(a) introducing a reformer feed gas mixture comprising at least one hydrocarbon and steam into one or more catalytic reactors in a reformer, each of the one or more reactors having an inlet and an outlet, reacting the reformer feed gas mixture in a steam-methane reforming reaction and water-gas shift reaction under reaction conditions effective to form a reformate comprising H 2 , CO, CH 4 , and H 2 O, and withdrawing the reformate from the one or more catalytic reactors;
wherein for a plurality of times, the method comprises
(b) measuring an outlet temperature, T outlet , representative of a temperature at the outlet of the one or more catalytic reactors for each time of the plurality of times;
(c) determining a temperature approach to equilibrium for the steam-methane reforming reaction at the outlet of the one or more catalytic reactors for each time of the plurality of times using the measured outlet temperature, T outlet ;
(d) calculating an empirical model-based temperature approach to equilibrium from reformer operating data and an empirical model based on historical operating data for a model reformer for each time of the plurality of times, wherein the model reformer is the reformer or another reformer; and
(e) comparing the temperature approach to equilibrium to the calculated empirical model-based temperature approach to equilibrium for each time of the plurality of times;
wherein steps (b) through (e) are repeated for the plurality of times.

2. The method according to claim 1 wherein, for each time of the plurality of times, the step of determining the temperature approach to equilibrium for the steam-methane reforming reaction comprises:
determining a reformate composition representative of the reformate withdrawn from the one or more catalytic reactors; and
calculating an equilibrium temperature, T equilibrium , from an equilibrium constant for the steam-methane reforming reaction at the reformate composition representative of the reformate withdrawn from the one or more catalytic reactors; and
wherein the temperature approach to equilibrium is calculated from the outlet temperature, T outlet , and the equilibrium temperature, T equilibrium .

3. The method according to claim 2 wherein the reformer feed gas mixture is formed from a hydrocarbon feed and steam, and wherein the step of determining the reformate composition representative of the reformate withdrawn from the one or more catalytic reactors comprises:
determining a hydrocarbon feed composition representative of a composition of the hydrocarbon feed via composition measurements;
determining a flow rate of the hydrocarbon feed via flow rate measurements of the hydrocarbon feed;
determining a flow rate of the steam via flow rate measurements of the steam; and
calculating the reformate composition using chemical element flow rate balances, the representative hydrocarbon feed composition, the flow rate of the hydrocarbon feed, the flow rate of the steam, and a water-gas shift equilibrium constant evaluated at the measured outlet temperature, T outlet .

4. The method according to claim 3 wherein the reformer feed gas mixture is formed from a H 2 feed in addition to being formed from the hydrocarbon feed and the steam, and wherein the step of determining the reformate composition representative of the reformate withdrawn from the one or more catalytic reactors comprises:
determining a flow rate of the H 2 feed; and
wherein the reformate composition is calculated also using the flow rate of the H 2 feed.

5. The method according to claim 3 further comprising:
measuring a methane concentration representative of a concentration of methane in the reformate withdrawn from the one or more catalytic reactors;
wherein the reformate composition is calculated also using the representative methane concentration.

6. The method according to claim 5 further comprising:
measuring a flow rate representative of a flow rate of the reformate;
wherein the reformate composition is calculated also using the representative flow rate of the reformate.

7. The method according to claim 2 further comprising:
measuring a reformate pressure representative of a pressure at the outlet of the one or more catalytic reactors, wherein the equilibrium temperature is calculated using the measured reformate pressure.

8. The method according to claim 1 wherein the empirical model is formulated from historical outlet temperatures, T outlet, historical , for the model reformer for a historical plurality of times, and calculated historical equilibrium temperatures, T equilibrium, historical , for the model reformer for the historical plurality of times.

9. The method according to claim 1 wherein step (e) comprises:
calculating a characteristic operational value (ΔT residual ) from the temperature approach to equilibrium and the calculated empirical model-based temperature approach to equilibrium, the characteristic operational value including the difference and/or the ratio of the temperature approach to equilibrium and the calculated empirical model-based temperature approach to equilibrium; and
determining whether a change in the characteristic operational value represents an objective increase or decrease in the catalytic activity of the reforming catalyst.

10. A method for determining decreased and/or increased activity of reforming catalyst comprising:
the method of claim 1 wherein steps (b) through (e) are repeated during a time period where the temperature approach to equilibrium relative to the empirical model-based temperature approach to equilibrium for each time of the plurality of times differs by an amount for a selected period of time, the amount and selected period of time determined to indicate decreased and/or increased activity of the reforming catalyst.

11. The method according to claim 10
wherein the amount determined to indicate decreased activity of the reforming catalyst is an amount corresponding to an increase in a value of a residual temperature to equilibrium, ΔT residual , of 3° C. or more during the selected period of time, where ΔT residual =ΔT approach −ΔT empirical , where ΔT approach =T outlet −T equilibrium and corresponds to the temperature approach to equilibrium determined in step (c), where T outlet is the measured temperature representative of the temperature at the outlet of the one or more catalytic reactors ( 20 ), where T equilibrium is a temperature calculated from an equilibrium constant for the steam-methane reforming reaction at a reformate composition representative of the reformate withdrawn from the one or more catalytic reactors ( 20 ), and where ΔT empirical corresponds to the calculated empirical model-based temperature approach to equilibrium; and
wherein the amount determined to indicate increased activity of the reforming catalyst is an amount corresponding to an decrease in a value of a residual temperature to equilibrium, ΔT residual , of 3° C. or more during the selected period of time, where ΔT residual =ΔT approach −ΔT empirical , where ΔT approach =T outlet −T equilibrium , and corresponds to the temperature approach to equilibrium determined in step (c), where T outlet is the measured temperature representative of the temperature at the outlet of the one or more catalytic reactors ( 20 ), where T equilibrium is a temperature calculated from an equilibrium constant for the steam-methane reforming reaction at a reformate composition representative of the reformate withdrawn from the one or more catalytic reactors ( 20 ), and where ΔT empirical corresp

Assignees

• Air Prod & Chem

Inventors

• Esmaili Ali
• Isom Joshua David
• Singh Suyash

Classifications

• C01B2203/16

  Controlling the process · CPC title

• G01N25/28 Primary

  the rise in temperature of the gases resulting from combustion being measured directly · CPC title

• C01B3/38

  using catalysts · CPC title

• C01B2203/0233

  the reforming step being a steam reforming step · CPC title

• C01B3/48

  followed by reaction of water vapour with carbon monoxide · CPC title