Questions regarding the nitrogen airtightness testing process after loading the hydrogenation unit?
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My company is building a new hydrogenation unit (currently under construction). Regarding the nitrogen leak testing of the reaction system after the catalyst is installed during the commissioning process, the research department says that this testing should be carried out in two stages at different pressures. Phase 1: System pressure: 1.0 MPa ； Phase 2: System pressure: 3.5 MPa. I would like to ask the experienced colleagues in hydrogenation: during the airtightness testing at 3.5 MPa of nitrogen, is it necessary to start the hydrogenation furnace to heat up the system? Also, at what point during the startup process should the reaction system be subjected to isothermal heat tightening? :o
Displacement and airtightness steps: (1) Displace the reaction system three times with nitrogen, then take samples for analysis until the oxygen content meets the specified standards (O2
It depends on the situation; if the furnace is not to be heated, a cold nitrogen cycle will suffice. If heating is required, use hot nitrogen for heating and tightening: 150 degrees, 250 degrees
Hello, friend on the 2nd floor! I’m not quite sure what you mean; I have a few questions: 1. Are these requirements specified in your company’s operating procedures? Is the record you posted a genuine one? 2. During the startup process, is it not necessary to use a heating furnace in either the nitrogen gas tightness testing or the hydrogen gas tightness testing steps? :o 3. During the nitrogen airtightness testing, the maximum pressure reached was 6.0 MPa. Are you using high-pressure nitrogen? Is it the compressor again? What type of compressor is it? (I heard from some well-known experts in China that \"using a new hydrogen compressor to increase the pressure of low-pressure nitrogen, the maximum pressure cannot exceed 3.5 MPa\". I’m not sure if this is true.) ) This post was last edited by ぁRed Blue Pencilぁ on 2009-2-24 15:48 ]
Hello, friend on the 3rd floor! The furnace drying process was carried out during the initial airtightness testing and drying of the reaction system, before the catalyst was loaded into the reactor (in my setup: first startup)! Once the CAT is loaded into the reactor, it should no longer be necessary to bake the furnace! ? Also, the heat setting temperatures you mentioned are: 150 degrees and 250 degrees ； What is the system pressure usually maintained at this time, in MPa? :handshake
I heard from some well-known experts in China that \"using a new hydrogen compressor to increase the pressure of low-pressure nitrogen, the maximum pressure cannot exceed 3.5 MPa.\" I’m not sure if this is true The expert you’re talking about must be all talk and no action; those who spout such things on site are usually worthless. The molecular weight of nitrogen is 28, while that of hydrogen is 2, so it’s impossible for the pressure of nitrogen to reach that of hydrogen when using a reciprocating compressor to increase pressure. It’s clear from the expert’s statements on site that they lack any real expertise
Brother upstairs, could you explain the reasons why you disagree with this view? Thank you! :handshake
During the airtightness test at 3.5 MPa with nitrogen, ignition for heating is not required. If catalyst drying is to be carried out next, ignition and heating will be required, during which thermal tightening can be performed. If necessary, during subsequent hydrogen-sealed heating, it can be re-tightened after oil is introduced.
First, introduce nitrogen at a pressure that is 1.5 to 2 times higher than the normal pressure; there’s no need for precision in this regard. The airtightness should be maintained for one day and night. For the hydrogen phase, conduct leak testing in the key areas. Perform both airtightness checks and leak tests; if time permits, do these operations twice. Once all related tasks are completed, the system can be put into operation. Fill it with nitrogen for displacement, then raise the temperature to around 200 degrees to carry out thermal tightening. Do this in stages, performing multiple rounds of thermal tightening, and also conduct leak testing in the key areas. Once everything is fine, adjust the temperature to the process-specific value and let the bed dry for a while – the duration can be set at any length of time, as long as it’s more than 12 hours. Next, use hydrogen; the time required for hydrogen to activate the catalyst depends on the specific process requirements. At the same time, use a handheld combustible gas detector to check for leaks. Once everything is in order, feeding material into the system is ready to proceed
During the thermal tightening of the reaction system, is the system pressure maintained at 3.5 MPa? Some experts say that during heat tightening, the system pressure must be reduced to 2.0 MPa before it can be carried out! I wonder if this is a requirement stemming from this? Additionally: I would like to ask whether, during the airtightness testing at 3.5 MPa with nitrogen, if the heating furnace is not turned on and the system pressure is raised directly to 3.5 MPa, this would violate the requirements regarding temper brittleness for Cr-Mo steel? What about the requirement that \"the pressure in the reaction system does not exceed 3.5 MPa until the lowest temperature at any point on the reactor wall rises above 135°C\"? :o
Is it necessary to use a hydrogen injection furnace to heat up the system during the airtightness testing under 3.5 MPa of nitrogen? Several conditions need to be met: 1. The system replacement is successful, with an oxygen content of less than 0. 5% ； ⒉There is no issue with the airtightness of the hydrogen system ； ⒊The compressor has passed the trial operation and can operate normally ； ⒋The gas system is airtight and the gas replacement process has been completed successfully; the gas is supplied to the heating furnace and can be used properly ； ⒌The heating furnace has reached the temperature rise conditions ； Then, the hydrogenation furnace can be activated to raise the temperature of the system. Also, at what point during the startup process should the reaction system be subjected to isothermal heat tightening? Following the furnace heating curve, the system is heated to 250 degrees and 350 degrees for isothermal heat tightening.