Operations and issues after alkaline cleaning of oils
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I have a few questions for everyone: in our hydrogenation process, is it necessary to wash the oil with water after alkali washing? Will the alkali remain in my oil and contaminate our products? How to detect whether there is pollution? What should be done if there is contamination?
After alkaline cleaning, it needs to be washed with water as well. Oil products require a neutral pH; after alkaline cleaning, the pH becomes alkaline, so the alkali has to be removed
Thank you to the person above; so, what’s a suitable amount of water for washing after the alkali wash?
I tested for sodium ions in the oil after alkaline cleaning today, and no presence was detected. Does this mean that water washing is no longer necessary after alkaline cleaning? Also, I would like to ask whether an alkali wash at around 5% could cause corrosion to pipelines and equipment? What are the requirements for the material? Are there any requirements for selecting a pump?
There is corrosion, but it’s not severe; you can rest assured as its corrosion margin is generally around 2.0 mm.
But now I doubt the results regarding the sodium ion content in the oil after alkali washing; after the alkali wash solution and the oil are allowed to separate, it seems impossible that no sodium ions remain in the oil phase at all
It is related to the testing method; generally, after sampling, it is washed with distilled water, and then the acidity or alkalinity of the water is tested.
Strictly speaking, after alkali washing of the oil in catalytic hydrogenation and other types of units, it is necessary to wash it with water again to maintain a neutral pH value for the oil. But now there are few wash processes available, and many design institutes no longer design such processes.
Does the moderator mean that there’s no need to rinse with water after alkali washing? Does neutrality of oils no longer serve as an indicator of oil quality? Also, I would like to ask the moderator: what is the appropriate ratio of alkali solution to oil? This post was last edited by New Life Propositions on 2009-2-18 12:50.]
The ratio of alkali to oil depends on the process used, as well as on the content of sulfides or acidic substances in the oil; it is generally between 1/5 and 1/3； Water washing generally requires careful design, and determining the amount of alkali present in the oil is crucial. I would like to ask the original poster what analytical method was used to conclude that no sodium ions were detected; conventionally, \"washing with distilled water and then testing the acidity or alkalinity of the water\" is a method that makes it difficult to detect sodium ions, especially in cases where the sodium ion concentration is already at the ppm level.
Dear poster: Nowadays, design institutes no longer include a washing process in the design of hydrogenation units; one method for removing the acidic components in oils is through stripping in a distillation tower； The second method is to remove it using low-temperature or high-temperature desulfurizers.
Thank you for your reply. We subject the alkali-treated oil to vacuum dehydration and then use ICP to measure the sodium ions in the oil; the level is below the detection limit, at less than 5 ppm. I would like to ask that since the concentration of alkali used in the treatment is relatively low, below 5%, what effects will it have on the oil if no further water washing is carried out after the alkali treatment?
It seems difficult to establish a correlation between the level of Na+ in oil products and its impact on downstream equipment. It is generally believed that an excessive amount of Na+ ions in oil products can cause scaling or corrosion in downstream heat exchange equipment. As the poster mentioned, the sodium ion content in the oil has exceeded the detection limit; it is below 5 ppm, so it should have little impact. The standard we generally use is a level below 1 ppm.
Alkali washing followed by water washing is a very effective method; this is basically the process used. Samples can be taken for analysis, with the aim of determining the degree of corrosion of the oil. If the corrosion level is 1A, that’s quite good