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PURPOSE: Purpose: This document describes the general guidelines for preparing the nitrogen bed for regeneration after a catalyst change. GENERAL: This document provides general guidelines for preparing the nitrogen bed for regeneration following a catalyst replacement. It outlines the general principles for preparing the nitrogen bed intended for regeneration after a catalyst change. GENERAL: General rules: Since hydrocarbons are present, neither preloading nor regeneration of the bed is required before dumping it. As there are no hydrocarbons present, precharging or regeneration is necessary before dumping the nitrogen bed. ENVIRONMENTAL, HEALTH AND SAFETY: Environmental protection, health, and safety: Nitrogen system units must be protected from contamination. Contamination of the nitrogen supply header by water, oxygen, or hydrocarbons can lead to potentially hazardous situations, especially during purification bed regeneration steps, equipment purging, or various other process steps. It is necessary to safeguard nitrogen system units against contamination. Contamination of the nitrogen supply source with water, oxygen, nitrogen, or other hydrocarbons can lead to potential dangerous situations, especially during hydrocarbon purification, equipment purging, and various other process steps. Nitrogen is an asphyxiant: Ensure adequate ventilation is available. Display warning signs at all locations where nitrogen is being purged to the atmosphere. Barricade the area in accordance with the policies for oxygen-deficient atmospheres during purging. Although nitrogen is considered inert, a vessel purged with nitrogen must be thoroughly flushed with air before physical entry. Nitrogen is lethal in asphyxiation cases, so it is necessary to ensure sufficient ventilation. Place warning signs at all locations where nitrogen is used to purge the atmosphere. During the purging process, shielding measures must be taken for each oxygen-deficient area. Although nitrogen is inert, sufficient air must be filled into the tank first before carrying out nitrogen purging. Controlled hydration by injecting steam at 2 mole % is required prior to opening the vessel. Exposure to moisture in the air will heat up the mole sieve and it could become an ignition source. Water absorption must be controlled by injecting steam at a concentration of 2% moles before opening the container. Molecular sieves will heat up due to exposure to water vapor in the air, and may become a source of fire. MP-67 streams vented to the flare must have an oxygen concentration of less than 3 mole %. Special attention must be paid to bringing back into service equipment that has been exposed to the atmosphere. The 3 mole % limit is based on the oxygen LEL for hydrogen. The oxygen concentration in the flare emissions must be below 3% by mole. It is particularly important to note that this portion of oxygen must be injected back into the return equipment to compensate for the amount released into the air. The 3% molar limit is based on the lower explosion limit of oxygen in hydrogen. This standard does not apply to small equipment that has been put back into service after being opened for maintenance, as such equipment does not contain enough oxygen. This standard applies only to equipment that has been opened for maintenance when its volume is greater than 20.9 cubic feet, in the case of a flare with a 12-inch riser. It is not applicable to the renewed use of small equipment for which sufficient oxygen cannot be ensured due to maintenance work. This standard applies only to the maintenance of Category I equipment with a volume greater than 20.9 cubic feet, such as torches equipped with 12-inch vertical pipes. For larger flares, use this formula: For bigger torches, apply the following formula: Equipment volume > (diameter of flare riser in inches/12”)3 x 20.9 (MP-67). Equipment volume > (inch diameter of the flare riser/12”) × 20.9 (MP-67). MP-50: When purging vessels, the maximum allowable working pressure of the vessel must not be exceeded; vessel rupture can occur if the pressure exceeds twice the maximum allowable working pressure. Excessive pressure in a tank can lead to death or life-threatening injuries. Extreme caution must be exercised when using N2 hoses for purging. (MP-50) When cleaning tanks, the maximum allowable working pressure must not be surpassed. If the pressure exceeds twice the maximum allowable operating pressure, the tank may rupture. Excessive pressure in the potential tank could lead to injuries or deaths. When using a nitrogen hose for purging, careful protective measures must be taken. (MP-50) MP-12 During hot bolting, the internal temperature of the vessel must be kept below the auto-ignition temperature of all hydrocarbons within a 50-foot radius. Re-insulation must be completed before the vessel temperature rises above the auto-ignition temperature of all hydrocarbons within that 50-foot radius. (MP-12) When using hot bolts for bolting, the internal temperature of the tank must remain below the auto-ignition temperature of all hydrocarbons within a 50-foot radius. Re-insulation must be completed before the tank temperature rises to the auto-ignition temperature of all hydrocarbons within a 50-foot radius. (MP-12) SPECIAL TOOLS AND MATERIALS: Special tools and materials include monogoggles, leather, rubber, or plastic gloves, as well as a respirator equipped with the appropriate dust filter. Refer to the maintenance procedures for the tools and equipment required for catalyst replacement. Goggles, leather, rubber, or plastic gloves, and a respirator equipped with an appropriate dust filter cartridge. Refer to the maintenance procedures for the tools and equipment required for catalyst replacement. Consult the maintenance procedures for the tools and equipment needed to replace the catalyst. PROCEDURE: Procedure: 1. Preparations: Preparation: 1.1 Ensure all maintenance work is completed and the Red Tag Master is ready to be removed. Make sure that all maintenance tasks are finished and that the isolation locks are taken off. 1.2 Ensure that the Return to Service Checklist is completed by maintenance. Make sure the maintenance work is finished using the Return to Service Checklist. PROCEDURE: (cont’d) Procedure: (Continued) 2. Purge and Low Pressure Leak Check of the Nitrogen Bed: (cont’d) Purging the nitrogen bed and checking for low-pressure leaks: (Continued) 2.1 Connect a nitrogen hose to the regeneration nitrogen inlet double valve and the vent valve. Attach the nitrogen hose to the dual valve at the nitrogen inlet for regeneration, as well as to the vent valve. MP-50 2.2 Slowly increase the pressure in the bed to between 350 and 400 kPa, then check for leaks. Repair any leaks that are found. (MP-50) Gradually raise the pressure to the range of 350–400 kPa, inspect for leaks, and fix all of them. (MP-50) 2.3 Close the Nitrogen supply. Turn off the nitrogen supply. 2.4 Use a noop and leak detector to inspect all fittings and flanges on the nitrogen bed. Repair any leaks as necessary. Use an endoscope and leak detector to examine all connections and flanges on the nitrogen bed. Repair any leaks as needed. 2.5 Vent the pressure to the atmosphere – Release the pressure into the air. MP-67 Note: Make sure the valve leading to the flare is closed; do not allow air to enter the flare header. The maximum oxygen limit in the flare header is 3 mol%. (MP-67) Note: Ensure that the valve connected to the flare is shut off, so as to prevent air from entering the flare header. The maximum oxygen limit in the torch tip is 3% molar. (MP-67) 2.6 Repeat steps 2.2 to 2.5 two more times to remove the air from the system. Repeat steps 2.2 to 2.5 twice to eliminate the air present in the system. 2.7 Disconnect the utility hose. Disconnect the common hose. 3. High Pressure Leak Check: Check for leaks at high pressure: MP-50 3.1 Ensure that the blind plate connecting to the regeneration nitrogen header is in the closed position, as the regeneration nitrogen heater and header are not designed to handle high pressures. (MP-50) Make sure the blind plate is in the closed position with respect to the regeneration nitrogen header, as neither the header nor the heater can withstand high pressures. 3.2 Use high-pressure instrument tubing to route high-pressure nitrogen from the vent on the inlet to the nitrogen dryer, to the vent on the nitrogen bed regeneration nitrogen inlet line. High-pressure instrument tubing is used to convey high-pressure nitrogen from the exhaust port at the inlet to the nitrogen dryer, and to the pipeline at the inlet for nitrogen bed regeneration. 3.3 Slowly increase the pressure in the nitrogen bed until it reaches the maximum allowable pressure at the nitrogen header. Increase the pressure in the nitrogen bed gradually until it reaches the highest pressure permitted by the nitrogen header. 3.4 Isolate and disconnect the high pressure tube. Separate and disconnect the high-pressure pipeline. 3.5 Ensure all open-ended vents are plugged. Make sure all open ventilation openings are covered. 3.6 Use a snoop and leak detector to inspect all flanges and fittings. Fix any leaks as necessary. Use an endoscope and leak detector to check all connections and flanges. Repair any leaks as needed. 3.7 Apply insulation blankets or temporary insulation to all exposed piping and vessel nozzles. Cover all exposed pipe ends and tank nozzles with fire-resistant blankets or use some other form of temporary insulation. MP-12 Note: This measure is necessary in order to enable hot bolting to be carried out later; however, the temperature of the exposed surfaces must not exceed 250°C, as this is the auto-ignition temperature of hexene. Re-insulation must be completed before the temperature of the vessel rises above the auto-ignition temperature of all hydrocarbons within a 50-foot radius. (MP12) Note: This step is required for subsequent hot bolting operations, and the temperature of the exposed surfaces must not exceed 250°C, which is the auto-ignition temperature of hexene. Re-insulation must be completed before the tank temperature rises to the auto-ignition temperature of all hydrocarbons within a 50-foot radius. 3.8 Complete the Return to service checklist – Finish the tasks outlined in the return-to-service checklist. 3.9 Regenerate the Nitrogen Bed as per operating procedure. Restart the nitrogen bed in accordance with the operating procedures. Note: MP refers to Mandatory Procedure, and RP refers to Recommended Procedure consistent with Layers of Protection Analysis (LOPA) as explained in the Process Design Data Report volume of the PDPs. Note: In the Process Design Data Report for PDPs, MP denotes mandatory procedures, while RP denotes recommended procedures that are in line with the LOPA layers. AUTHOR: Compiled by: ______________________ ISSUE DATE: Date of release __________________ REVISED BY: Modified by: _______________ LAST REVISED DATE: Last date of modification __________________ REVIEWED BY: Reviewed by: ________________ NEXT REVIEW DATE: Date of next review __________________