Some questions regarding the practicality of liquid chlorine emergency tanks
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This post was last edited by sunjl1981 on 2013-1-6 at 22:36. Today, I came across several issues related to chlorine gas leaks, which reminded me of a topic we used to discuss jokingly with friends regarding how to deal with such leaks. 1. When there is a chlorine gas leak, it’s an endothermic process; when the leak occurs through small holes, frosting or freezing can easily occur. On the positive side, this might even lead to the leak being sealed on its own, thus stopping the leakage. 2. When using chlorine gas cylinders, emergency tools must be available on site; the most important of these are leak-sealing equipment. (I won’t go into details; it’s specified in the operating procedures.) Well, if both of the above conditions are met, then I have a question: 1. What kind of leaks require chlorine gas cylinders to be placed in the emergency tank? In what situations should leak-sealing equipment be used to stop leaks? 2. Are there any size specifications for emergency pools? Are there any requirements for the concentration of liquid caustic or lime water? What should be the optimal amount? 3. The liquid chlorine tank pushed into the emergency pool is essentially meant to release its contents on its own, so as to avoid any other mistakes. So, when more than a ton of liquid chlorine leaks and reacts with the alkaline water in the emergency tank, acid-base neutralization generates a large amount of heat, causing the temperature inside the liquid chlorine tank to rise and the pressure to increase… Is it possible for all of the liquid chlorine or chlorine gas that is released quickly to be reacted away before it can leak into the air? 4. Where there are pits, there must be fences; many companies enclose their emergency tanks with fences. But will this ensure that, in the event of a chlorine leak, the tanks can still be opened and the chlorine tanks allowed to roll in? Of course, it’s also not possible without a fence. 5. In many companies, the emergency tanks are not located very close to the areas where they are used or stored. Some emergency pools are essentially designed specifically for liquid chlorine tanks. I’m not sure whether it’s possible to get inside them quickly in the event of a liquid chlorine leak – for example, if the tank is lying on its side while the pool is built vertically, how can one get inside? Even the smallest tank must hold 1 ton, right? Labor wasn’t very useful at that time. 6. Continuing with step 3, the temperature inside the liquid chlorine tank rises, and the pressure also increases; the vaporization rate of liquid chlorine is very fast… Could this lead to a sharp increase in nitrogen trichloride? Will it explode? I have had many questions regarding the design and practicality of this liquid chlorine emergency tank. I would appreciate it if experts with on-site experience could provide some insights. Thank you! I originally posted this in the Safety Engineering forum, but no one paid any attention to me... Ugh. I’ve moved it here, hoping to meet some enthusiastic friends here. #+++
To be honest, after working in the chlor-alkali industry for so many years, this alkali tank has never been used once. Firstly, as a traditional regulatory requirement, it must be implemented; even for inspection purposes, it is necessary to have it installed. Secondly, this alkali tank was also created to address problems that cannot be solved; it is a last resort and does not represent an ideal solution. Such as the tearing of the gas cylinder body or the breakage of the cylinder valve. Explain a problem: On older liquid chlorine cylinders, both the front and rear plugs were made of fusible plugs; when the temperature inside the cylinder rose above 60 degrees Celsius, the fusible plugs melted and released chlorine gas. Therefore, the chlorine release point can still be ensured. And the setup of the alkali ponds was also stipulated by the standards of that era. In the late 1990s, the fusible plug was removed and replaced with a solid wire plug; as a result, when the pressure inside the cylinder increased, there was no mechanism for releasing that pressure. The only options were to break the threads of the cylinder valve to allow pressure to escape, or for the cylinder to explode – which is certainly a drawback. People often discuss the practicality of this alkali tank. In my opinion, even if it is used only once in a lifetime, and even if the steel cylinder causes a sharp rise in temperature inside the tank, the alkali solution present there can still absorb any chlorine that leaks out, thereby reducing the risk of accidents. This makes it worthwhile to have such a tank. Moreover, after the steel cylinder is placed in the alkali tank, humans can introduce more alkali solution and compressed air into the tank to stir things around, which helps to create time and space for dealing with any accidents that might occur. Returning to the safety of gas cylinders: These cylinders are designed with a high degree of redundancy and comprehensive protective measures, and there are also many regulations to govern their use. The pressure testing and cleaning of cylinders every 2 years, the mandatory retirement period of 12 years, as well as each inspection of the cylinders, are all key factors in ensuring their safe use. Therefore, the safety of gas cylinders does not depend on purely technical measures, but rather on people’s safe behavior and sense of responsibility. Everyone, especially the younger ones, must not be careless, and must never doubt the safety facilities established by those who came before us. Friend, when you get older, you too will have the thought of \"getting more afraid the more you do it.\"
It is very necessary to have a chlorine emergency tank. Process pipeline: Add alkali and water; it is best to install a spray nozzle at the top ； It is usually a concrete structure, with anti-corrosion treatment applied. Adding railings is for routine safety reasons; alkali concentration: it should generally not exceed 15% ；
It’s useful. I’ve encountered a situation where the stem of a cylinder valve broke, preventing the valve from closing, which led to a large leak of chlorine gas; in the end, the cylinder was pushed into an alkali tank
The emergency tank we want to have has also never been used; it’s just left outside without a roof, so rainwater flows in directly when it rains. It seems that the concentration of the alkaline solution has also never been analyzed. It has completely become a mere ornament
The emergency tanks in most facilities are merely for show; they’re hardly ever maintained. In actual use, they’re not utilized unless it’s absolutely necessary, right? I have indeed experienced the shocking scene of a valve stem breaking in a bottle valve, resulting in a massive release of chlorine gas; however, I was wearing a gas mask, and it was sufficient to fit a hex head on the valve or block it off with a clamp. There is enough time to push the gas cylinder into the emergency pool to use tools to deal with it. After pushing it into the emergency tank, there are still many issues that need to be addressed in a short time, which is quite troublesome. For example: sufficient amounts of alkali must be added to the tank, but many facilities don’t have pipes connected to the emergency tank – so how can the alkali be added? When the liquid chlorine in the cylinder leaks to a certain extent, the cylinder will float on top of the absorbing liquid, which may result in the leak site being exposed to the air and causing direct release of chlorine gas; therefore, it is necessary to keep the leak site below the surface of the absorbing liquid at all times. This is also a very serious problem ； Therefore, I suggest that it is best not to put them into the emergency pool, unless the emergency rescue tools fail or are not effective. Of course, that’s a different story if the emergency pool is well-designed!
Our company uses an accident gas cylinder treatment room; its structure consists of a fully enclosed concrete construction, with rolling shutter doors, and fiberglass fans are used to remove the vaporized chlorine along with any exhaust gases. For minor leakage issues, steel cylinder leak-sealing tools are used for handling; for more complex cylinder-related problems, they can be resolved inside the dedicated handling room. If the issue cannot be resolved, the rolling shutters can be closed at any time, which is very effective