Naphtha Steam Reforming Catalyst Reduction with Methanol

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Procedure for Naphtha Steam Reforming Catalyst Reduction with Methanol

Scope

This procedure applies to the in situ reduction of VULCAN Series steam reforming catalysts using methanol cracking to form hydrogen over the catalyst in the steam reformer.

The procedure is likely to be applied to plants using only heavier feeds (e.g.: LPG and/or naphtha) and some combination of VULCAN Series catalysts.

Introduction

A small number of steam reforming plants do not have an available source of the commonly used reducing media (e.g.: hydrogen, hydrogen-rich off-gas, natural gas). These plants will usually operate on LPG and/or naphtha feed only where cracking of this hydrocarbon is not usually advised for reduction of the steam reforming catalyst ...

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Naphtha Steam Reforming Catalyst Reduction with Methanol

  1. 1. GBH Enterprises, Ltd. Naphtha Steam Reforming Catalyst Reduction with Methanol Process Information Disclaimer Information contained in this publication or as otherwise supplied to Users is believed to be accurate and correct at time of going to press, and is given in good faith, but it is for the User to satisfy itself of the suitability of the Product for its own particular purpose. GBHE gives no warranty as to the fitness of the Product for any particular purpose and any implied warranty or condition (statutory or otherwise) is excluded except to the extent that exclusion is prevented by law. GBHE accepts no liability for loss, damage or personnel injury caused or resulting from reliance on this information. Freedom under Patent, Copyright and Designs cannot be assumed. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  2. 2. Naphtha Steam Reforming Catalyst Reduction with Methanol Scope This procedure applies to the in situ reduction of VULCAN Series steam reforming catalysts using methanol cracking to form hydrogen over the catalyst in the steam reformer. The procedure is likely to be applied to plants using only heavier feeds (e.g.: LPG and/or naphtha) and some combination of VULCAN Series catalysts. Introduction A small number of steam reforming plants do not have an available source of the commonly used reducing media (e.g.: hydrogen, hydrogen-rich off-gas, natural gas). These plants will usually operate on LPG and/or naphtha feed only where cracking of this hydrocarbon is not usually advised for reduction of the steam reforming catalyst. In such circumstances, the plant may be designed to use the installed steam reforming catalyst to crack methanol to provide hydrogen for the reformer catalyst reduction. A once through method should be used to avoid the potential of methanation of carbon oxides produced in the methanol cracking. By control of the steam to methanol ratio and reformer exit temperature, oxidized catalyst cracks methanol to generate hydrogen which then effects a degree of catalyst reduction. Once some reduced nickel is present, methanol cracking becomes efficient and the period in which methanol is observed in the process condensate is kept to a minimum. Procedure 1. Ensure the primary reformer catalyst is heated in a nitrogen flow to above the dew point of the process stream. Once this temperature is exceeded by at least 50°C (90°F), continue heating with process steam. The system pressure should be in the usual range for the reformer start-up circulation loop (typically 10 – 15 bara). Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  3. 3. 2. Heat the reformer to a measured inlet temperature in the range 475 to 500°C (887-932°F) and a measured exit temperature of 780 to 800°C (14361472°F). If the plant design does not allow the inlet temperature to attain this level, then the inlet temperature should be as high as possible within the constraints of the plant. Temperature losses to the point of exit temperature measurement are usual at this low load of operation and the actual tube exit temperature will be higher than these values. Regular (1/2 hourly) inspections, ideally with an accurate IR pyrometer, of the reformer are necessary to check for possible overheating. 3. At the above temperatures, control the steam flow through the primary reformer insofar as this is possible to remain within tube skin temperature limits and to satisfy the ratio of steam to methanol as specified in (4) 4. Inject methanol at an initial rate to satisfy a steam to methanol molar ratio of an absolute minimum of 25:1. This will be sufficient to carry-out the catalyst reduction, but the process will be slow and methanol will be present in the condensate for the period. To minimize the time to produce hydrogen and limit the amount of methanol in the condensate, lower molar ratios of steam to methanol should be targeted in the range 20:1 to 18:1. 5. Process condensate containing methanol will need proper attention. Initial levels of methanol could exceed 1000 ppmw, but will reduce quickly once cracking occurs over the reforming catalyst 6. Maintain continuous methanol injection at the required rate for at least one (1) hour. 7. Take samples for analysis of the reformer exit for hydrogen and process condensate for methanol every 30 minutes over the first two hours of methanol injection. Thereafter, reduce the frequency to every 60 minutes for as long as necessary. 8. If no hydrogen is detected after 2 hours and the methanol levels in the process condensate remain high (>>100 ppmw), then the molar ratio of methanol to steam is possibly incorrect and/or the reforming temperature is low. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  4. 4. 9. Once hydrogen is measured, the H2O/H2 molar ratio should be recorded (from a combination of analysis and calculation of the amount injected and cracked methanol). The target point is when the H2O/H2 molar ratio enters the target reduction range of 6:1 – 8:1. The molar ratio may be allowed to go as low as 4:1 without cause for concern in terms of the catalysts. 10. Once the H2O/H2 molar ratio is in the range 6:1 – 8:1, maintain the methanol injection rate. Continue to analyze at 60-minute intervals and calculate the H2O/H2 molar ratio in the exit. 11. Maintain reducing conditions (H2O/H2 molar ratio in the range 6:1 – 8:1) for the following times depending on the recent shutdown history of the catalyst. See Table 1. 12. Following this, introduce hydrocarbon feed as described in the Operating Manual for VULCAN Series Naphtha Steam Reforming Catalysts. Table 1 – Catalyst Reduction Times Catalyst Steaming Period (Hours) <3 3-8 >8 Fresh Catalyst Charge Period of Reduction (Hours) No reduction required 6 hours of reduction 12 hours of reduction 18 hours of reduction Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
  5. 5. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com

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