Formaldehyde production
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Fume oxidizers are prone to leaks at the tube bundles and tube sheets when started up; how do you deal with this issue? Is there any way to avoid it?
In addition to improving the structure of the oxidation furnace, the following points should be paid attention to: 1. During startup, the oxidation furnace should be preheated in advance using steam (or hot water)； 2. During normal operation, it is necessary to maintain a stable temperature in the oxidation furnace to prevent excessive fluctuations in furnace temperature ； 3. When stopping, gradually reduce the load and slowly lower the furnace temperature.
Yes, when we start the machine, we use steam to heat it to 150-170 degrees, then increase the amount of air and methanol, and ignite it. Once ignited, the temperature rises to 650 degrees in about 2 minutes. The temperature change is so severe that the pipes can’t handle it and start leaking; basically, there are leaks every time we start the machine. The temperature is generally kept fairly stable
Silver-phosphorus formaldehyde furnaces experience a rapid rise in temperature when started up, but good oxidation furnaces can last for five to six years, or even more than ten years. I wonder how long your furnaces have been in use? In a short period of time, if the operations are carried out properly, there may also be issues with the materials used for the heat exchange tubes and tube sheets; welding technology is also quite important.
Switch to the iron-molybdenum method, hahaha – no need to shut it down for a year
It’s the third year now; in total, more than 200 pipes have been sealed. It’s time to replace them. Ugh, it’s worrying. I’m still figuring out the best way to do this; it seems fine, but maybe I just haven’t realized the issue yet
The mainstream process used domestically for producing formaldehyde is the silver-based method, which can be considered a mature technology; the key element here is the reactor
What is your specific energy consumption? Has the methanol content been analyzed by chromatography?
In the production of silver-based formaldehyde, methanol is used in excess; under normal production conditions, the oxygen-to-alcohol ratio is approximately 0.38~0.42
The key lies in the support method for the shell side in the heat exchange section at the lower part of the reactor, as well as the design for even fluid distribution. CFD simulations are used to determine the most suitable support types, such as baffle rods and hollow rings, in order to reduce temperature field inconsistencies between the heat exchange tubes in the central area and those in the peripheral areas, and to prevent stress-induced damage to the tubes and tube sheets.