The boiling range of the pure methanol product exceeds the specified limits
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The boiling range of the pure methanol products manufactured recently does not meet the specifications; the maximum value reached is 4. I’m not sure whether this is due to analytical issues or something else. I would appreciate advice from experts on how to ensure that the boiling range of the products meets the required standards during production ? Thank you! ! ! ! !
I’m not familiar with your distillation process; a high boiling range definitely indicates a high content of heavy components. If all other test results show excellent quality, then check whether the testing methods are appropriate, and the temperature meter also needs to be calibrated
Thank you for your advice. In the case of triple-column distillation, the moisture content in the sample analyzed as mentioned above is 0.4, and its specific gravity is only 0.791. What could be the problem? The unit in the analysis report below is a defective product; what could be the cause of this issue? Report date: June 24, 2008. Test subject: Pure methanol. Testing criteria: Moisture content, %: 1.39 – Boiling point, °C: 7.6 – Water solubility: – Clarity: – Density (at 20°C), g/cm3: 0.795. Notes: The boiling point and density values exceed the specified limits! Last edited by ddfmy on 2008-7-4 at 19:43
It would be best if you could list all the analysis data from the tests – what are the initial boiling point and dry point? The moisture content is 1.39%, and the boiling range is 7.6, which is indeed quite high. When the moisture content is above a certain level, a boiling range measurement is usually not carried out. A low initial boiling point indicates an abundance of light components; in such cases, it’s necessary to increase the reflux temperature of the pre-tower and reduce the reflux flow rate, while also increasing the venting from the pre-tower. A high dry point suggests an abundance of heavy components. I’m not sure whether your tower operates under pressure or at atmospheric pressure. In my opinion, the high boiling range is mainly caused by the high moisture content. It’s important to increase the reflux flow rate, control the temperatures in the upper parts of the tower and at the top of the tower so that they don’t exceed the design values, keep the pressure at the top of the tower from dropping too low, increase the extraction of fusel oils, and properly control the heat source at the bottom of the tower. Personal opinion, for reference only
The test results show that the heavy components are above the acceptable level; the density of methanol is usually between 0.792 and 0.793... The main reason is high temperature, which causes the heavy components to rise to higher levels
It’s obvious from the list that the water content is extremely high! According to national standards, it is a defective product! Is it still necessary to determine the boiling range? ? The pressure and temperature certainly haven’t reached the criteria for producing qualified products! It’s hard to determine the reason just by looking at the product! Lower the moisture content first!