How to perform nitrogen displacement

First, determine the volume of the container; if it is to be used for maintenance work (hot work), the gas supply volume must be at least 3 times the volume of the container to be displaced

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In accordance with the production process, materials should enter and exit through the feed and discharge ports, so as to ensure that the entire production system is fully replaced. At the same time, it is necessary to control the replacement time; it is best to check at the outlet whether the gas parameters have met the required standards by the end of this process!

Nitrogen purging plan for the device – Items to be confirmed before nitrogen purging: (1) It is necessary to confirm that the system is airtight before carrying out nitrogen purging. (II) The system blind plates and gaskets are installed correctly. (III) Install warning signs indicating the introduction of nitrogen into the tank at the appropriate locations in each system, and notify the relevant departments. II. Precautions during nitrogen displacement: (I) Use pressure building tests for displacement; do not fill while simultaneously releasing gas, and ensure that the discharge point is far away from the filling point. (II) The processes must be properly defined, and the systems need to be strictly isolated. (III) The far-point drain must be discharged to prevent the formation of dead zones. (IV) Replacement qualification standard: Oxygen content analysis less than 0.5%. (5) Analysis of samples taken from the highest and lowest drain points. 3. Arrangement of personnel for the work: All shifts 1, 2, 3, and 4 are involved; the supervisors of these four shifts are responsible for ensuring safety and the quality of the work, as well as keeping records of the nitrogen displacement process. 2 Assign tasks according to the sequence of permutations. The replacement of utility gases is carried out jointly by the last 4 teams. Step 4: Nitrogen replacement (I) Nitrogen replacement in the light-end removal unit 1. Process setup: Isolate the light-end removal system (T-101, 2-T-101, D-101, 2-D-101, D-102, T-102, 2-T-102); use the feed valves of M-201 and 2-M-201 as boundaries (open all control valves and stop valves within the system). 2. Replacement: Connect rubber hoses to the drain ports of pumps P-001 and P-101, use nitrogen at a pressure of 0.08 MPa to purge the system, then vent the gas through various drain ports and exhaust outlets until the pressure drops to 0.02 MPA. Repeat this process of pressurizing and venting; the replacement is considered successful when oxygen content, as determined by analysis, is less than 0.5%. After the replacement is approved, the system is pressurized to 0.05 MPA, and all valves are closed. (II) Nitrogen purging of the desulfurization unit 1. Process setup: Isolate the desulfurization unit system (including R-201A, R-201B, D-202, D-203); open all control valves and shut-off valves within the system. 2. Purging: Open the nitrogen main pipe valve, as well as the drain valves of pump P-204 and the reactor feed line. Use nitrogen at a pressure of 0.08 MPA to purge the system, then release the gas through the various drains and exhaust vents until the pressure drops to 0.02 MPA. Repeat this process of pressurizing and releasing until the oxygen content, as determined by analysis, is less than 0.5%, at which point it is considered acceptable. After the replacement is approved, the system is pressurized to 0.05 MPA, and all valves are closed. (III) Nitrogen purging in the degassing unit 1. Process setup: Isolate the desulfurization unit system (including T-301 and 2-T-301), and open all control valves and shut-off valves within the system. 2. Connect a tubing for backwashing to pump P-302 and FV1301; use nitrogen to apply a pressure of 0.08 MPA, then release the gas through the various drainage ports and exhaust vents until the pressure drops to 0.02 MPA. Repeat this process of pressurizing and releasing; the test is considered successful if the oxygen content, as determined by analysis, is less than 0.5%. After the replacement is approved, the system is pressurized to 0.05 MPA, and all valves are closed. (IV) Nitrogen purging of the acetylthiophene stripping system 1. Process setup: Isolate the acetylthiophene unit system (including T-302, T-601, and the exhaust system with its buried tanks). Open all control valves and stop valves within the system. 2. Purging: Connect rubber hoses at the drain points of pump P-303, P-601, pump P-205, and pump P-206, and use nitrogen to apply a pressure of 0.08 MPa. Then release the gas through the various drains and exhaust outlets until the pressure drops to 0.02 MPa. Repeat this process of pressurizing and releasing; the mixture is considered qualified if the oxygen content, as determined by analysis, is less than 0.5%. After the replacement is approved, the system is pressurized to 0.05 MPA, and all valves are closed. (V) Nitrogen purging of the utility system 1. Process setup: Isolate the utility system (including medium-pressure and low-pressure steam systems, medium-pressure and low-pressure condensate systems, circulating water systems, and fire water systems). Open all control valves and stop valves within the system. Connect rubber hoses at the drain points of each system pipeline, use nitrogen to apply a pressure of 0.08 MPA, and then release the gas through the various drains and exhaust ports until the pressure drops to 0.02 MPA. Repeat this process of pressurizing and releasing; the test is considered successful if the oxygen content, as determined by analysis, is less than 0.5%. After the replacement is approved, the system is pressurized to 0.05 MPA, and all valves are closed. 5. Continued nitrogen displacement work: It is recommended to carry out additional pressure applications every three to four weeks, in line with the company’s production schedule. The device system should also be inspected and recorded from time to time. The specific procedures for nitrogen displacement and pressure supplementation are the same as those mentioned earlier. Nitrogen Purging Worksheet: Serial Number, System Section Range, Operating Pressure, Operating Time, Oxygen Content, Pressure Holding Time, Inspection Signature. 1: ; 2: ; 3: . The plan I have prepared is for reference only

Generally, in larger systems where the amount of nitrogen is not sufficient, the method of repeatedly increasing and decreasing pressure is often employed； When a large amount of nitrogen is present, continuous purging with discharge at dead corners can be employed

Is nitrogen generally used to displace the previous materials in large-scale production facilities?