Device shutdown purging

First, purge the pipeline of the medium with a high freezing point, in sections

Cleaning must be carried out in accordance with the shutdown plan and cleaning principles, by cleaning the heavy oil lines first and then the light oil lines, etc., following the required segmented approach.

For purging the pipeline sections, your oil needs a place to go; should it be sent through the line for heavy crude oil? Especially with heavy crude oil, it’s possible to purge each heat exchanger individually

Purging has requirements regarding both steam flow and pressure. If there is sufficient steam available in the pipeline network, purging can be carried out simultaneously for various systems, but there are principles and precautions to follow when performing steam purging

Inject steam in full once the steam pressure is sufficient; conduct inspections in segments, and pay attention to draining condensate from the lowest points

If all lines are purged, firstly, the amount of steam used is excessive, which prevents ensuring an appropriate steam pressure in each line; secondly, there are often dead corners in the lines that cannot be thoroughly cleaned, leading to residual deposits. It is best to have a comprehensive purging plan in place before starting the purging process, to carry out purging in stages, and to keep proper records of it. This ensures that the purging is done properly while also avoiding chaos that could lead to repeated purging efforts.

I. Organizational structure for purging inspection work II. Principles and requirements for line purging: Unified planning and thorough arrangement； Clarify responsibilities and assign them to specific individuals ； Operate properly to leave no blind spots ； Emphasize key points and avoid any hidden risks ； Thoroughly empty it – 100% guaranteed ； Ensure the device is ready to start at any time. III. Line cleaning sequence (based on the last shutdown, including steam purging and air purging): 1. Steam purging. The oil in the pipelines and equipment tanks must be thoroughly purged. 2. The wind blowing ensures that there is no water accumulation inside the pipelines and equipment. 3. The water system is treated with air separately. IV. Preparation Work 1. Make arrangements to obtain crude oil by getting empty tanks, as well as side-line product tanks with low liquid levels (Chang-1, Chang-2). 2. Contact the dispatch team to ensure that the steam pressure is ≮ 0.70 Mpa and the low-pressure value is ≮ 0.2 Mpa. 3. Prepare the required tools (hoses, pliers, wrenches, wire). 5. The leak points have been marked. 6. Fire-fighting equipment is fully prepared and placed in designated locations. 7. Keep the floor drain unobstructed. 8. The air compressor supply system is ready. V. Requirements for device purging 1. Upon receiving the instruction, steam purging must be carried out in strict accordance with the specified plan. There must be unified command and coordinated action. 2. During the purging process, it is essential to maintain a uniform speed to avoid damaging the equipment and pipelines. 3. It must be thorough, ensuring no omissions, no oil retention, and no oil leakage. 4. The purging of each container must meet the requirements for working with open flames. Equipment such as heating furnaces and heat exchangers must be pressurized multiple times as required to check for leaks. 5. The locations where blind plates are removed and installed must be recorded separately. And they are all 8-character blind plates. 6. Appropriate control points must be selected for all pipelines, and purging should be carried out following the \"three long and two short\" principle, with at least 3–5 cycles, to ensure that there is no oil or water remaining inside the pipelines, thus meeting the conditions required for working with fire (pay attention to the purging sequence of interconnected pipelines). During line cleaning, it is essential to remove all oil from devices such as control valves and heat exchangers (for coolers, the cooling water must be drained first). 7. Thoroughly test for leaks in all the side lines and return lines of the pressure reduction system; the pressure reduction and vacuuming system should also be checked for leaks during tower purging. (Including the normal third line) After scanning is complete, release pressure at the lowest point to drain all the condensate water. 8. Clean and inspect for leaks in the furnace fuel oil system. 9. Clean and inspect for leaks in the furnace tubes and oil transfer lines inside the furnace. 10. There must be a designated person in charge of the pipelines, and signatures must be obtained after purging. VI. Operation Process (I) Precautions for steam purging: 1. Avoid using high-pressure and low-pressure steam to purge the same pipeline at the same time, to prevent oil crossover incidents. If multiple operations are to be carried out simultaneously (such as stripping tower and intermediate reflux, or line cleaning at the pump outlet), it is necessary to ensure unobstructed flow and prevent pressure buildup. 2. Before scanning, close the conduits of each orifice plate. For process pipelines equipped with meters and control valves, a bypass line should be used first; once the entire pipeline is connected, steam can be used to quickly push the oil out, after which the bypass line can be switched off. Before starting the steam, the condensed water in the steam must be drained. When introducing steam, it is necessary to first remove the condensed water to prevent water hammer, and then supply the steam slowly. At the same time, when cleaning low-temperature pipelines, an appropriate drainage point should be selected along the pipeline to prevent water hammer or steam hammer. 3. During the line cleaning process, pay attention to the steam pressure; multiple pipelines should not be fed with steam at the same time – one pipeline should be closed after each one has been cleaned. During the steam purging process, it is necessary to concentrate the steam and carry out the purging in the order of shutdown, starting with the heavier and more critical components first, and then those located higher or lower. For pipelines with a long length, compensating joints can be installed in between. 4. After completing the line cleaning, relieve pressure at a low level to empty it; do not allow condensate to remain in the pipelines. For equipment and pipelines that cannot be emptied or drained completely, the flanges can be unscrewed. 5. Steam purging must be thorough to ensure no oil remains, and the system must be emptied of water to create favorable conditions for air purging. 6. When the cleaning line passes through the heat exchanger, it is possible to first send it into the heat exchanger to remove the oil from within it; once the entire line is connected, the lines can then be connected one by one in the order specified by the process. (If the flow path of the heat exchange system is long, it is possible to start with two sets of lines first.) 7. The upper and lower water valves of the cooler through which the steam passes should be completely closed, and the drain valve should always remain open to remove any remaining water as well as the steam generated during cleaning. 8. During steam purging to remove oil, except for the furnace reduction system, try not to allow oil from other pipelines to enter the tower. 9. To ensure that the pipeline is thoroughly purged, it is necessary to close the end valve, apply pressure, and then quickly open it again; this process should be repeated 3–5 times to guarantee the quality of the purging. 10. Keep thorough purging records, assigning each pipeline to a specific person to ensure no omissions. 11. During the purging process, each piece of equipment, each pipeline, each valve, and each flange must be carefully inspected to determine whether there are any potential hazards. Registration is carried out simultaneously, and finally, corrections are made. VII. Purging procedure: 1. Normal Line 3: ① Steam is supplied at the outlet of Pump 9 → then to Valve 15 → Valve 6 → the plant control valve (FRCQ301) → the small platform valve assembly → Tank 4/1, 2 ； (High-pressure steam) (Drain point) (Drain point) ② Steam after the outlet valve of Tower 3 → Pump 9 → Exchanger 15 → Cooler 6 → Outlet control valve, small platform valve assembly → Tanks 4/1, 2 (Tower 3 is connected to Tower 2 at the platform located after the outlet control valve.) (High-pressure steam) (Drain point) (Drain point) (Drain point) Key inspection points: 1. Valves: Side-line valves on the tower wall, cleaning valves ； Inlet and outlet valves of heat exchanger coolers, bypass valves, drain valves, inlet and outlet valves of pumps ； Check for leaks in control valve 2 and all pipelines. 3. Check whether the control valve is in good condition with no leaks. 4. Verify that there is no deformation of the valve, and that the large and small gland seals as well as the flange gaskets have no leaks. 5. After confirming that cleaning is complete, first close the tank inlet valve, then relieve pressure and empty it for inspection to prevent backflow. 6. Reduce pressure and use stripping to pump fluid to pump -13 for thorough evacuation; the side line on the wall of the middle reboiler must be tightly closed, as well as the pump outlet valve, to prevent any contamination during the stripping process. 7. When performing regular cleaning operations, the side line valves on the tower wall must be tightly closed to avoid contamination during stripping. After the operation is complete, valve -1 must be closed tightly to prevent connection with the reduced-pressure pipeline. Signature of the assigned staff: Signature of the team leader: Signature of the workshop supervisor: