The problem of amine/alkali solution entrainment after \"double dehydration\" of liquefied gas

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As is well known, in coking or catalytic units, liquefied gas must undergo \"double dehydration,\" but after this process, the liquefied gas still contains amine and alkali solutions! Undoubtedly, this is a widespread problem; it has not yet caused insurmountable issues in the subsequent processes, big or small, and many manufacturers do not pay enough attention to it! But this problem does exist, and now there is a good and simple solution – by adding coagulators. Many people will say that they were already aware of this method and had indeed added such devices, yet the problem has not seen any fundamental improvement. My answer is: That’s because no good design firm was found; it’s that simple – a good piece of equipment. In the face of the customer’s doubts, that’s what I told him as well – I needed to clear the coalescer’s name. After amine washing of liquefied gas, some amine will naturally remain in the liquefied gas, at levels of perhaps several hundred to several thousand ppm, even with the best amine washing processes. This is because the interfacial tension between liquefied gas and amine solution is very low, belonging to the category of low interfacial tension. As is well known, the lower the interfacial tension of a two-phase fluid, the more difficult it is to separate. This is also why no good coalescer has been able to achieve the desired removal efficiency, as they have ignored a very important design factor – interfacial tension. It’s only natural that the results aren’t good. After alkali washing of liquefied gas, a water wash is usually added to remove the alkali, but there are two problems: 1, the alkali cannot be completely removed by water washing, so some alkali remains in the liquefied gas. 2. The liquefied gas, after being washed, undoubtedly has an increased water content. So, just like with the deammoniation solution, is there a device that can remove the alkali content from liquefied gas after alkaline washing to a very low level – a level that is at least comparable to, or even lower than, the Na+ content after water washing? In that case, can we just skip the washing step? We have calculated that the main costs of water washing are as follows: water, tanks, pumps, and electricity. The cost of these four items over a year is more than enough to purchase a device for producing dealkalizing solution, and the same goes for the second and third years. . . . Is it the net profit of the equipment? We have already resolved the above two issues in practical operations. We have indeed managed to solve the problem with low investment!