What material is used for melt-state strong alkali reactors?
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To develop a certain special material, molten KOH is required. It turns out that the laboratory used special stainless steel, which broke down very quickly. Using special nickel can meet the requirements of the test. Now that the experiment has been successful, it’s time to move on to the pilot-scale testing phase. However, there is a challenge: it’s difficult to determine what type of material would be suitable for use as a reactor vessel for molten strong alkalis at around 1000 degrees Celsius, in order to ensure safety. Even if the pilot-scale production can be carried out without considering costs, what about when it comes to industrial-scale production? Let’s discuss this – what materials are cost-effective to use?
Let me add that while using special nickel can meet the requirements of the tests, the material tends to soften easily, and its strength cannot be guaranteed at all. It’s okay for laboratory use, but it’s absolutely unsuitable for use as a reactor.
Since special nickel can meet the requirements of the tests, you can use a composite plate of special nickel and stainless steel for the reaction vessel; this approach meets both the demands related to corrosion resistance and strength, while keeping the cost acceptable.
That’s a laboratory; it has only a protective gas pressure, and the reaction releases very little heat. In this way, it becomes soft after just two uses; of course, industrial use is not possible as the strength cannot be guaranteed. Based on your plan, it would explode in a few hours. Because in our experiments, the reaction time is only a few minutes. The entire process takes only two or three hours; the special nickel material softens, while with stainless steel, there is simply no perforation that occurs. For industrial use, of course it’s not very useful. I wonder if any expert here has experience using molten strong alkalis; please share your insights first. Thank you!
OP, I’m not sure if you’ve resolved your issue yet? I’m facing this problem now as well; melting with strong alkalis at 300-400 degrees – I’m not sure what reactor conditions to use. Please give me some advice too!
The temperature you mentioned can be achieved with nickel materials; generally, N5 is used for that purpose
In industry, nickel is used for the production of solid alkalis, but under atmospheric pressure. Regarding the 1000 degrees mentioned by the poster, composite panels can be used if the pressure is not high. What the friend on the second floor suggested is the most cost-effective solution; if that still isn’t sufficient, consider importing special materials from abroad
Try using a refractory lining. The composite steel plate solution is indeed quite economical, but can a metal substrate withstand high temperatures of 1000 degrees Celsius?
At this temperature, if strength is taken into account, it can be said that no material can withstand 1000-degree molten sodium hydroxide. Refractory materials, including graphite, alumina ceramics, zirconia ceramics, silicon carbide ceramics, and silicon nitride ceramics, are all not suitable.
The lining does not contribute to the strength; it serves only to resist high temperatures and provide insulation. The outer container shell provides the strength, just as refractory bricks are used in gasification furnaces.
It’s not about strength; among refractory materials, none can withstand the corrosion of sodium hydroxide at 1000 degrees.