The \"life-or-death race\" before the start of operation of a hydrogenation unit: If one fails these two tests, who would dare to turn on the furnace?

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The 25th National “Safety Production Month” in 2026: Everyone should talk about safety and know how to handle emergencies; identify and eliminate potential risks. -------------------------------------------------- 01 On the eve of operation commencement: The “high-stakes exam” within the plant is approaching. https://mmbiz.qpic.cn/mmbiz_png/RRz5icUSmRfKzzN6DGG4cWGbpVuODiahJGBicOoxFtHrcoJW6QXfldxzNTnZHo74icyKIyYVm6ImItIKhd6RvYm7cVOkFkqfJHoeMBwBcibwOZH4/640?wx_fmt=png&from=appmsg#imgIndex=2 If you have been to an oil refinery, you must have heard the old workers say: “Each time operations start, it’s like going through hell.” ”From construction to commissioning, a hydrogenation plant goes through countless processes, but what really makes operators nervous is always those few \"critical tests\" carried out before the actual introduction of oil. Today, we are going to talk about two of these practical tests that can be described as \"life-or-death races\" – the rapid cooling hydrogen system test and the emergency pressure relief test of the reaction system. One tube is for cooling to save lives, and the other is for releasing pressure to enable escape. If one fails these two exams, no one will dare to turn on the heating furnace that follows. Exam 02: Installing \"precision air conditioning\" in reactors https://mmbiz.qpic.cn/sz_mmbiz_png/RRz5icUSmRfIfYLgKuzCa9yD3bpW0vGo3yQhljVac2GA3UoLAkmSXSE4Tkmjq9VCefK6UsWAeu8EZ6AiasypAeuDvLHcvIaIJI6HXicdCs2ibOw/640?wx_fmt=png&from=appmsg#imgIndex=4 What will be tested? The catalyst bed in the hydrogenation reactor has an extremely high temperature. Once the reaction gets out of control, the bed temperature soars like a runaway horse—that is the dreaded phenomenon known as \"runaway temperature\". At this point, rapidly cooled hydrogen is the only \"fire extinguisher\": a stream of cold hydrogen is drawn from the outlet of the circulating hydrogen compressor and directly injected between the various bed layers to cool down the reaction by \"pouring cold water\" on it. But the question is: Is this “air conditioning system” effective? Does the valve respond properly? Is there enough cold hydrogen? Is the temperature drop response fast? The rapid cooling hydrogen system test is essentially a comprehensive inspection of this \"life-saving air conditioning system\". How do you take the exam? The testing conditions are quite \"strict\": the reactor has been filled with catalyst, the system has passed hydrogen gas tightness tests, and the pressure is raised to 8.0 MPa – which corresponds to the pressure conditions at a depth of 800 meters underwater. Then, the operator began to \"test step by step from bottom to top\": increasing the temperature control valve for cold hydrogen from 10% to 100%, raising the setting gradually just like stepping on the accelerator ； For each gear change, the cold hydrogen flow rate and temperature changes for each bed layer are recorded ； At the same time, check whether the valve position matches the signals in the control room – if it is indicated as 50% on site, it must also be displayed as 50% on the DCS; one cannot say one thing while doing another” ； It is also necessary to measure the lag time for temperature changes – how many seconds pass between the valve opening and the bed layer cooling down? This determines whether the system will be able to react in time if something really goes wrong. After the test, you can’t shut all the valves all at once; that would cause too large fluctuations and could lead to leaks at the flanges. It takes 10 minutes to shut it down gradually, just like an experienced driver applying the brakes for a smooth landing. In one sentence: This test is to ensure that every setting of the air conditioner can be controlled precisely, so that it can save lives when extreme temperatures occur. Test 03: Conducting an “evacuation drill” for the installation. If the rapid cooling hydrogen test is akin to “regular maintenance,” then the emergency pressure relief test is like a “field first-aid exercise” – it simulates extreme accidents such as uncontrolled temperature rise in the reactor or equipment leaks and fires, to determine whether it’s possible to release pressure in the shortest time possible and thus prevent explosions. What will be tested? The operating pressure of hydrogenation units is usually between 8 and 20 MPa, with high-temperature and high-pressure hydrogen gas and oil-gas flowing within them. Once out of control, it becomes a \"hot hydrogen bomb\". The function of the emergency pressure relief system (also known as the 0.7 MPa/min pressure relief system) is to reduce the system pressure by 0.7 MPa per minute once the ”emergency button” is pressed, thereby quickly lowering the pressure and temperature and causing the reaction to stop. This test is designed to verify three things: Is the size of the pressure relief valve plate correct? Can the designed pressure relief speed be achieved? Is the interlocking system reliable? When the control room button is pressed, do the valves on site move? Can the torch system withstand it? With the hydrogen and oil-gas escaping in an instant, can the torch burn them? Will backfire occur? How do you take the exam? ——The first step of this tense \"seven-step process\": record the meter readings, the high pressure at the outlet of the recirculating compressor, as well as the temperatures at various points in the system and in the flare condensate tank – these are the \"baseline data prior to a diagnostic check\". Step 2: Valve inspection – Close the manual valve of the emergency pressure relief control valve. The operator inside gives commands to open the valve to 50% or 100% capacity, while the person outside monitors the valve; it must open when instructed to do so and close when instructed to stop, otherwise an instrument technician should be called immediately to take a look at it. Step 3: Open the “life channel” – first open the valve downstream of the control valve, then the valve upstream (to prevent devices with a lower pressure level downstream from being “pushed over”). Switch the fresh hydrogen control valve to manual mode in advance to prevent the upstream hydrogen production unit from being \"vacuumed out\" during pressure release. Step 4: Simmer at low heat to test the flare valve. Gradually increase the valve opening to 5%, 10%, and 30% to test the flare line, for 3 minutes each time. Send someone to check the torch combustion – there should be no black smoke, no backflow of flame, and no explosions. Step 5: Full-speed sprint to test limits – Gradually return to the operating pressure, then increase it again step by step from 5%, 10%, 30%, 50%, 70%, until it reaches 100% full capacity; reduce the system pressure all at once to 3.0 MPa. During this process, it is necessary to record every minute: by how much has the system pressure dropped? How much has the differential pressure across the reactor bed changed? Has the pressure in the torch line exceeded 0.4 MPa? Is the pipeline displacement large? Step 6: Stop at the red line – If the pressure release rate exceeds the maximum allowable value specified in the design (0.7 MPa/min), shut the valve immediately! Contact the instrument technician for calibration before proceeding. It’s like when a race car exceeds the safe speed limit and one must ease off the throttle. Step 7: Review and archive. Once the experiment is complete, analyze all the data to determine the relationship curve between the pressure reduction rate and valve opening degree, and create a graph for archiving. This is the “genetic blueprint” of the device, which must be referred to for every operation thereafter. Finally, press the red emergency pressure release button in the control room and test it again—to confirm that the \"one-button escape\" function really works. 04 The task of collecting exam papers after the tests are over: https://mmbiz.qpic.cn/sz_mmbiz_png/RRz5icUSmRfJESguXJlrHicm5Mw5KD9v6eic2ALN3bEicpAqeWM4DzrTmia9ouFnLr76vu9Rop8Qia9ficSFYaH3vw0u2szL2rJ6FJDKYXOJM6WIhY/640?wx_fmt=png&from=appmsg#imgIndex=8. Even after passing both major exams, it’s not possible to start working right away. There are a few things to do to wrap things up: reset the interlock system, restart the heating furnace, and gradually bring the temperatures at various points in the reaction system back to their levels before pressure release ； Start the new hydrogen compressor and gradually raise the system pressure back to the design pressure at a rate of 1.5 MPa/h – it cannot be done too quickly, as the equipment cannot handle such rapid increases ； A dedicated person should be stationed at the emergency pressure relief valve, keeping watch over it like a sentinel and maintaining constant communication with the control room ； The operator closely monitors the differential pressure across each bed; if the reactor’s differential pressure exceeds 0.7 MPa, pressurization is stopped immediately to investigate the cause. Only once all of this is secure can we move on to the next stage – catalyst presulfurization. 05 Conclusion: There is no rehearsal for safety; every drill is a real-life scenario. https://mmbiz.qpic.cn/mmbiz_png/RRz5icUSmRfJH7KtI5lEDfibRV3ObK9nib1XITzQdVvWa7aic2mc03nbvsIRYGz3icicn8qCMDG1s5SjsOuCbgWn4BIedqVZZj3d7Dial2FCDlTWVs/640?wx_fmt=png&from=appmsg#imgIndex=10 The rapid cooling hydrogen test and the emergency pressure relief test are the two most tedious yet most critical procedures carried out before a hydrogenation unit is put into operation. It’s tedious because it requires repeated recording, step-by-step debugging, and constant verification ； They are thrilling because they simulate extreme scenarios that could take lives in real-world production. The experienced masters often say, “Sweat more in peacetime, and bleed less in wartime.” ”Under a hydrogen pressure of 8.0 MPa, test each valve to ensure it is in place, plot each curve accurately, and verify the reliability of each interlock – this is not just a formality; it is a way of providing a \"life-saving insurance policy\" for the equipment, the operators, and the entire plant. After all, in the face of high-pressure hydrogen, there is no such thing as “more or less”; it’s either “acceptable” or “not acceptable”. This article is compiled based on the operating guidelines for hydrogenation refining units and relevant engineering practice materials. Find it useful? Forward this to your colleagues in the hydrogen industry – let’s go through these two \"life-or-death\" challenges together before starting work!