There are two theories about the specific cause of the accident. One is the explosion of the reactor and the other is the explosion of the hydrothermal kettle.
Let me briefly tell you the difference between the two types of equipment. In fact, these two types of equipment can be used for high-pressure reactions. If there is a difference, the hydrothermal kettle has a simple structure and the reaction kettle is more complicated.
In this picture, the left side is the hydrothermal kettle, and the right side is the reaction kettle
. These two types of equipment are generally made by hollowing out the middle with a whole piece of steel rod, and the wall thickness is very thick. , The pressure-bearing capacity is very strong, under normal circumstances, as long as the explosive is not boiled in the reaction kettle, the whole kettle will not be blown up. At most, the lid will fly out or the material will spray out. The closest I was to deleting my account and re-training was when the pressure gauge of the reactor flew out and almost had a headshot.
The biggest difference between the two is that the structure of the hydrothermal kettle is too simple. In fact, it is a pot that can be sealed with PTFE as an anti-corrosion lining. When in use, add various materials to the kettle, and then heat it in a water bath or an oil bath. This equipment is generally used for high temperature and high pressure reactions that do not require stirring. The price of the hydrothermal kettle is relatively cheap, about a hundred dollars. A laboratory can buy multiple at the same time, and the experiment is conducted in parallel, and the efficiency is still relatively high. But the key point is that the structure of the hydrothermal kettle is too simple. In order to reduce costs, the simplest hydrothermal kettle has no pressure gauge, no pressure relief valve, no temperature probe, not to mention safety valve, bursting discs, etc. Measures up. Therefore, some answers mentioned that the victim was killed by the lid of the water-heated kettle because the water-heated kettle was not completely cooled. In fact, the water-heated kettle was forcibly opened while the interior was still under high pressure. If it is a hydrothermal kettle, it is indeed possible, because there is no instrument to tell you whether the temperature in the kettle has completely cooled down and what the pressure is. What's more, it is possible that the water-cooling process is directly carried out during the operation, which causes the water-heated kettle to be actually cold outside and hot inside, which is more prone to judgement errors.
In the final analysis, the structure of the hydrothermal kettle is too simple.In fact, there are some more complicated hydrothermal kettles on the market that can be equipped with pressure gauges and pressure relief valves, and the price is a little more expensive. As long as there is a pressure gauge hanging on the hydrothermal kettle, telling people that the pressure inside is 70 kg, or there is a pressure relief valve, you can manually open the valve first to reduce the pressure, and such a tragedy will not happen.
Another thing that is more fascinating is that if there is pressure in the container, it is actually difficult to open either the reaction kettle or the hydrothermal kettle by means of manpower. It is unbelievable that a girl can open the cauldron in this situation.
Relatively speaking, the structure of the reactor is much more complicated. First of all, the reactor is stirred. The original stirring is the place where leakage is relatively easy. However, the laboratory-scale autoclave generally uses a magnetic coupling with stirring, so the problem is also Not big. In addition, the reactor itself refers to the design of some pressure vessels . In addition to the pressure gauge and thermometer, there are safety measures such as safety valves and bursting discs. In addition, the reactor generally has a pressure relief valve. If you open the kettle in a hurry to see the results of the experiment, you can actually open the pressure relief valve to slowly release the gas in the reaction kettle, and the kettle can be opened normally when the pressure reaches normal pressure. It can be said that if there is a low-level error in the process of using the reactor to dismantle the kettle under pressure, it is completely that the user is not aware of safety.
Of course, although the reactor safety measures are relatively in place, I think there are still potential safety hazards in the actual laboratory use.
First of all, when designing the reactor, some teachers with a background in chemistry will not refer to the relevant regulations at all. The designed reactor scheme is flawed, and some people don’t even know that a safety valve is required. .
In addition, there is a common phenomenon that the relief valve of the safety valve is not connected to the outside. This is related to the planning of the laboratory. The so-called safety valve is a special valve, which is next to the pressure gauge in the figure above. Similar to our pressure cooker, if the pressure in the reactor exceeds a dangerous value, this valve will open to discharge the gas in the reactor. However, in reality, the safety valve design of many experimental reactors is unreasonable. The exhaust is directly in the room. If it is a toxic and harmful gas, it will endanger human health. If the gas contains flammable and explosive gases,Discharge into the room may be directly detonated by indoor electrical appliances, so that the safety valve becomes a dangerous valve instead. What’s even more funny is that when some people design the reactor, the position of the safety valve is facing the person. You can screw a valve in front of the reactor and copy the data. The safety valve is directly facing your face. The safety valve takes off, and the high-temperature and high-pressure gas directly greets people's faces. The design is extremely unreasonable.
There is another problem that cannot be ignored, that is, if you refer to the pressure vessel regulations, the instruments of such high pressure vessels, including thermometers, pressure gauges and safety valves, must be checked regularly. Because the instrument will be broken, it will fail, we must always make sure that they are in normal working condition. But in reality, in actual scientific research and production, almost no one, including myself, would ignore this issue. When everyone is busy with scientific research tasks and projects, who would have the mind to consider this issue. But this is a potential safety hazard. When I was a graduate student, there was an accident in the next laboratory. The cause of the accident was simple. Crystallization occurred during the reaction. After a long time, the crystallization blocked the pressure gauge and safety valve pipeline. , This valve failed, and the lid of the kettle was directly topped. In fact, the laboratory should pay more attention to the inspection of the instrument, because the experiment is performed frequently, and the material situation is complicated and changeable. In the end, there are many irregularities in the operation of the students, and the wrong screw force may affect the instrument and equipment. Life expectancy leads to an increase in the failure rate. In this case, more attention should be paid to the inspection of the instrument.
There is also the problem of corrosion. In chemical and chemical laboratories, a set of equipment is often used for multiple reactions. The material of the equipment may not meet the needs of all tests, and there will be a phenomenon of "just do it once or twice, it doesn't matter". Existing equipment may be corroded after long-term operation. In fact, uniform corrosion is also good. The more terrifying thing is local corrosion. When I was working before, an old engineer told me about such a case. A reactor leaked, and the whole body was almost intact, but there was a very small crack at the bottom. This kind of local corrosion is very hidden and dangerous.
Experimental safety accidents can be said to be impossible to prevent. When we go to school, we will more or less hear news about where people have died again.
If you want to improve, I think there are a few points that you can actually pay attention to:
1. The laboratory in the university is too crowded due to various reasons, a space of 60 square meters,It can put two rectification devices, two chromatographs, two reaction kettles, plus a muffle furnace, and some other equipment, and it can also make people work. Such a crowded environment is prone to stumbling, mixed materials, and leakage of water and electricity. Moreover, the crowded and messy environment is not conducive to the equipment maintenance mentioned before.
2. Due to various reasons, or because of business, or because of academic orientation, many research group projects are too complicated. A set of reactors serves different reaction materials and conditions. The staff will do this today and do that tomorrow, which will increase virtually. Because of the probability of equipment failure, everyone often thinks that equipment is easy to break. Three-year graduate students repair the equipment in two years. This is the case. At the same time, if the personnel are not concentrated, the possibility of errors is greater. In fact, I think universities don’t do a lot of topics, and it’s useless to do it anyway.
3. Then, safety education should not only be done once at school or after an accident. It should be done regularly. Everyone is inert, and everyone knows fritters. After safety education a month after the safety education, they will be cautious. Normally, human psychology should be like this, so safety education should be done regularly and often.
4. It is recommended that the chemical and chemical laboratory should be equipped with specialized mechanics and electricians. It is also possible for several research groups to share one. I know that many professors of the older generation had limited conditions at the time. When they were studying, they repaired the equipment and picked up the electricity by themselves. They might think that for the current graduate students, this will not be possible or that, as if they are degraded. However, from the perspective of efficiency, there is a specialization in the technical industry. If a student is a graduate student for three years, he can't do something for two years because of equipment problems and then repairs the equipment, it is a real waste.
In the end, I hope to spend some money to get the equipment for the experimenters. If it is an explosion in the hydrothermal kettle according to other answers, the tragedy will not happen if the kettle is equipped with a pressure gauge.
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