Regarding the airtightness issue of the newly installed equipment
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We are building a new hydrogenation pilot plant. I have been working on drafting a test plan recently. There is such a problem with the airtight part of the device. The operation manual provided by the process package supplier describes the airtightness for the reactor (under various operating pressures of 16 MPa to 22 MPa) and the high-pressure and low-pressure separators as follows: a) Close the inlet and outlet valves of the compressor, and fill it with nitrogen up to 0.1 MPa. b) Hold for 1 hour, check for leaks, then release pressure. c) Recharge nitrogen to 0.1 MPa, then release pressure. Repeat the replacement steps until the oxygen concentration at all sampling points is checked
As a supplementary point, our operating temperature is 430°C; therefore, at what pressure and temperature does thermal tightening begin under airtight conditions?
If a circulation of hydrogen can be initiated at 0.6 Mpa, that’s acceptable; the gas tightness can be ensured through drying of the reaction system. Additionally, if the hydrogen is kept under high pressure, it is necessary to raise the temperature in order to prevent backfire in the reactor. Thermal tightening of reaction systems is generally very difficult, as they operate under high pressure; in many cases, hydraulic wrenches are used for reinforcement, as manual thermal tightening does not provide sufficient strength
In actual production, nitrogen can be used for low-pressure airtightness testing, and then hydrogen can be used for airtightness testing at system pressure. In most plants, the nitrogen pressure is between 2.0 and 2.5 MPa; there are also plants where the nitrogen pressure exceeds 10 MPa (though this is less common). Nitrogen can be used to displace oxygen from within the system
Generally, it is difficult to raise the pressure of nitrogen to 5.0; when it is hard to use nitrogen for pressurization, hydrogen can be used instead. However, before switching to hydrogen, the heating furnace and catalysts must be completely dried. Prevent catalyst reduction accidents.
The typical heat-setting temperature is 250 degrees Celsius; it is possible to perform another heat-setting at 300 degrees Celsius.
This step is related to the material of the reactor; it is necessary to ensure that the wall temperature of the reactor remains above a certain value when the pressure inside the reactor reaches a specific level. For example, the pressure should be greater than 3.0 MPa, and the wall temperature should be no less than 90°C. I’m not sure if you understood