High Temperature Shift Catalyst Reduction Procedure
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High Temperature Shift Catalyst Reduction Procedure

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High Temperature Shift Catalyst Reduction Procedure
The catalyst, as supplied, is Fe2O3. This reduces to the active form, Fe3O4, in the presence of hydrogen when process gas is admitted to the reactor.

1. The mildly exothermic reactions are:

3 Fe2O3 + H2 ========= 2 Fe3O4 + H2O

3 Fe2O3 + CO ========= 2 Fe3O4 + CO2

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High Temperature Shift Catalyst Reduction Procedure High Temperature Shift Catalyst Reduction Procedure Document Transcript

  • GBH Enterprises, Ltd. VULCAN VSG-F101 High Temperature Shift Catalyst Reduction Procedure 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
  • REDUCTION AND OPERATION OF VULCAN VSG-F101 The catalyst, as supplied, is Fe2O3. This reduces to the active form, Fe3O4, in the presence of hydrogen when process gas is admitted to the reactor. 1. The mildly exothermic reactions are: 3 Fe2O3 + H2 ========= 2 Fe3O4 + H2O 3 Fe2O3 + CO ========= 2 Fe3O4 + CO2 2. If steam is not present, reduction of Fe3O4 to metallic iron takes place: Fe3O4 + 4 H2 ========= 3 Fe + 4 H2O (endothermic) Fe3O4 + 4 CO ========= 3 Fe + 4 CO2 (slightly endothermic) 3. Metallic iron must be avoided because it catalyses the following very exothermic reactions: CO + 3 H2 ========= CH4 + H2O 2 CO ========= CO2 + C The reduction process is a fairly simple one: 1. Purge the reactor free of air with inert gas. 2. If possible, heat the catalyst bed with dry gas until the process gas condensation temperature is exceeded. Alternatively, heat the catalyst with process gas and allow the effluent gas to go to the vent. Pressurization to system pressure can be carried out at any time during the reduction. 3. Raise the catalyst temperature to 575oF at up to 100oF per hour. Reduction begins around 300oF and is nearly complete at 575oF. 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. The CO shift reaction will begin around 575oF and the observed temperature rise will depend upon the inlet CO content and steamto-gas ratio. The inlet gas must contain less than 15% CO (wet basis) because the maximum allowable temperature at this stage is 930oF. The subsequent steps are only applicable for VULCAN Series VSG-F101 catalysts, which are low sulfur materials. Raise the inlet temperature to ideally 750oF and hold for 1-2 hours. Reduce the inlet temperature to the normal operating inlet, typically 680-700oF. The catalyst is now fully activated and the process gas can now be passed forward to the next process step. OPERATION In early life, the catalyst is usually operated in the inlet temperature range of 680700oF. The optimum should be determined on-line by increasing the inlet temperature in steps of 10oF and measuring the exit CO content - after steady conditions have been stabilized. For extended catalyst lives, the HTS should be operated at the minimum practical inlet temperature compatible with good CO conversion. As the catalyst ages and performance deteriorates it may be advantageous to elevate the operating temperature to minimize CO leakage. Although HTS catalysts are quite strong, even in the reduced state, condensation of steam-to-water on the catalyst should be prevented by keeping inlet process gas temperature well above the dew point. During short shutdowns, the catalyst may be left under process gas or steam at either operating or lower pressures. It may even be steamed, if necessary, to maintain operating temperatures. It is important to ensure air does not enter the vessel when the plant is shut down. Air re-oxidizes reduced catalyst causing an excessive temperature rise and catalyst damage. Typically H.T. Shift catalysts give lives of 4-5 years. 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
  • POISONS High temperature shift catalysts are not appreciably affected by those things that act as poisons to the other catalysts in the system. Instead, loss of activity is usually the result of deposition of boiler feed water solids and/or silica carry-over. These block the catalyst pores and prevent the reactant gas from reaching the catalytic sites. In extreme cases, the spaces between tablets in the upper part of the bed become clogged causing pressure drop problems. DISCHARGE If the catalyst is to be discarded, it does not require a special oxidation procedure before discharge. Once the vessel is depressured and purged free of process gas with steam, it is cooled to about 400oF. From there, inert gas replaces steam to cool the catalyst to the ambient temperature. A positive pressure of inert gas is held on the reactor to prevent air from entering. The catalyst is either dumped or vacuumed from the reactor. Water hoses should be available in case the catalyst heats up when exposed to the air. 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
  • 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