Distillation tower cleaning interlock scheme

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Scheme 1 for the cleaning of distillation towers – Conditions required for water-based commissioning tests: 1. The works within the scope of the commissioning tests must have been fully completed in accordance with the contents specified in the design documents as well as the standards set out in the construction and acceptance regulations； 2. All machines and pumps within the commissioning scope have passed individual testing successfully ； 3. The internal treatment, pressure testing, and tightness testing of the equipment and piping systems within the commissioning range have all passed ； The pipelines and equipment have been purged successfully, and the system’s airtightness test and vacuum pumping test have passed. 4. The electrical systems within the commissioning range, as well as the testing systems, automatic control systems, interlock systems, and alarm systems of the instrumentation devices, have all been inspected and tested to meet the required standards ； 5. The water-driven commissioning plan and operating procedures have been approved; the process parameters, alarm settings, and interlock settings specified in the commissioning plan have been confirmed and issued ； 6. Testing organizations at all levels have been established; the personnel involved in the testing have passed the necessary examinations and are working with valid certificates ； 7. The utility supplies required for the water-driven commissioning, such as water, electricity, nitrogen, and instrument air, can be supplied stably, and all necessary materials, testing instruments, and tools are already available ； 8. The site for the water-driven commissioning test has been completely cleaned up ； 9. All on-site instruments and remote transmission instruments have been calibrated successfully and are in normal operation ； 10. Filters are installed at the inlets of all pumps, and line filters are put into use ； II. Preparatory work before trial operation – Verification tasks 1. Verify that the temporary blind plates used for purging the pipelines and systems supplying circulating water, primary water, nitrogen, steam, etc., as well as those entering the area, have been removed ； Are the isolation valves between various systems closed? ； Whether the drain valve of the water injection tank is open. 3. Verify whether the reflux tank V101 (a temporary pipe is connected to the reflux tank to inject about 1500 mm of primary water) is filled with water. 4. Verify that the pump motor rotates in the correct direction ； The bearing operates without sticking or abnormal noises ； The pressure gauge is accurate and the valves are flexible and reliable ； Lubricant addition completed ； The turning gear is normal, and the packing gland is in order. 5. Ensure that the electrical, instrumentation, and safety automatic protection systems are flexible and easy to use ； The electrical and instrumentation pressure gauges are sensitive and accurate, while the valves are flexible and reliable. III. Detailed procedure for joint commissioning 1. Tower T101 ⑴ Start the reflux pump P102 to send the clean water inside the reflux tank (V101) to Tower T101 via the feed line ； ⑵When the liquid level in the bottom of the tower reaches around 600 mm, activate the steam self-regulating valve of this tower and add steam slowly; the system will then start to heat up. Make sure that the heating rate remains within 20–30°C per hour ； ⑶Once the liquid level in the tower bottom reaches 1500 mm, start the tower bottom pump P104 (with the AB pumps operating alternately) to circulate the cleaning water inside the tower bottom and return it there. ⑷Once the liquid level in the reflux tank V101 starts to rise, start the reflux pump P102 (with the AB pumps operating in alternation) to carry out a full reflux operation; pay attention to maintaining stable liquid levels in the reflux tank and the bottom of the tower ； ⑸After the distillation column of this system has been in operation for 2 hours, the feed rate to tower T101 is adjusted based on the liquid level, while simultaneously stabilizing the liquid levels in the various tanks and at the bottom of tower T101. Note: No cleaning water should be introduced into either the T101 side stream extraction pipeline or the product tank V401 ； 2. For Tower T201⑴, open the flange of the DN50 spare port at the top of V101, connect a temporary hose, and inject water into V201 once; close the water supply valve when the liquid level in V201 reaches 1400 mm ； ⑵Once a liquid level appears in the bottom of the tower, activate the steam automatic control valve for that tower and add steam slowly; the system will then start to heat up, with care being taken to keep the temperature increase within 20–30°C per hour ； ⑶Once the liquid level in the bottom of tower T201 reaches 600 mm, start pump P202, which is used for pumping the liquid from the bottom of the tower (with the AB pumps operating alternately). Also, open the recovery line of this pump to enable circulation of the liquid in the tank ； ⑷Once the liquid level in the reflux tank V201 starts to rise, start the reflux pump P201 (with the AB pumps operating in alternation) to carry out a full reflux operation; pay attention to maintaining stable liquid levels in the reflux tank and the bottom of the tower ； ⑸After the system’s distillation column has been operating for 2 hours, the feed rate to tower T201 is adjusted based on the liquid level, while simultaneously stabilizing the liquid levels in all the storage tanks and at the bottom of tower T201. IV. Issues to Note 1. Strictly control the liquid levels in each tower and reflux tank to maintain water balance within the system, ensuring stable circulation and preventing overheating or overpressure in the system ； Keep proper records of commissioning parameters such as pressure, temperature, flow rate, and liquid level ； Record any identified equipment defects and safety issues, and take action to address them. 2. When operating in water-linked mode, pay attention to the blockage status of each filter, and clean the filters promptly ； 3. The operation of the equipment must be carried out strictly in accordance with the operating procedures. Before starting, check whether the oil level and valves are at the required levels, and it is necessary to perform a crank test before startup. Pay attention to the device’s current level and operating conditions; overloading is strictly prohibited ； The pump is not allowed to run dry; the flow rate must be at least the pump’s minimum flow rate ； If any abnormality is detected, stop the machine immediately for inspection to resolve the issue ； 4. During the testing period, operators must follow instructions, strictly adhere to the testing plan and relevant regulations regarding job procedures; it is strictly prohibited to act on one’s own initiative or to make any mistakes in operation ； 5. It is strictly prohibited to carry out maintenance, welding, or tightening of connections under pressure ； 6. It is strictly prohibited to shut off the isolation valves located at the system pressure gauges, safety valves, etc., arbitrarily ； 7. During the commissioning process, strengthen on-site inspections to ensure that the readings on the on-site instruments match the data displayed on the DCS in the control room ； 8. During the testing process, operators must wear full personal protective equipment, pay attention to their own safety, and avoid all types of safety accidents such as falls and electric shocks. 9. After testing the vehicle, open the drain valve at the lowest position of the device to drain all the water from the system; the vent valve at the highest point of the system must also be opened (or the condenser’s vent valve should be opened). V. Tools required: F wrenches (4) ； 12-inch adjustable wrenches (3 pieces) ； Flashlights (2) ； Intercoms (2 units) ； Rubber hoses (2 packs) ；